Opensense
Eleventy
Peter deHaan
Touchless
Dropkiq
Dailycontributors
Serkan Holat
amit777
Khaled Salem
Sentry
Checkout Blocks
Customer IO
Emmanuel Cartelli
Microsoft
PakStyle.pk
Syntax Podcast
Cartelli Emmanuel
EscortA.com
Chudovo
Opensense |
- Eleventy |
- Peter deHaan |
- Touchless |
- Dropkiq |
- Dailycontributors |
- Serkan Holat |
-
amit777 |
- Khaled Salem |
- Sentry |
- Checkout Blocks |
- Customer IO |
- Emmanuel Cartelli |
- Microsoft |
-
PakStyle.pk |
- Syntax Podcast |
- Cartelli Emmanuel |
- EscortA.com |
- Chudovo |
-
user passed in scope
+{% increment %}, {% decrement %} changes this scope,
+whereas {% capture %}, {% assign %} only hide this scope
global scope used as fallback for missing variables
+The normalized liquid options object
+Throw when accessing undefined variable?
+Optionalscope: object | ContextOptionalsync: booleanOptionallookupType: LookupTypeOptionalcurrentFile: stringOptionalscope: object | ContextOptionalscope: object | ContextReturn an array of all variables including their properties/paths.
+Return an array of all variables including their properties/paths.
+Return an array of all expected context variables including their properties/paths.
+Return an array of all expected context variables including their properties/paths.
+Return an array of all expected context variables, each as an array of properties/segments.
+Return an array of all expected context variables, each as an array of properties/segments.
+Return an array of all expected context variables without their properties.
+Return an array of all expected context variables without their properties.
+Optionalfilename: stringOptionalfilename: stringOptionalscope: object | ContextOptionalrenderOptions: RenderOptionsOptionalscope: object | ContextOptionalrenderOptions: RenderOptionsOptionallookupType: LookupTypeOptionallookupType: LookupTypeOptionalscope: objectOptionalrenderOptions: RenderOptionsOptionalctx: object | ContextOptionalrenderFileOptions: RenderFileOptionsOptionalctx: object | ContextOptionalrenderFileOptions: RenderFileOptionsOptionalscope: objectOptionalrenderOptions: RenderOptionsOptionalscope: objectOptionalrenderOptions: RenderOptionsOptionalscope: objectReturn an array of all variables, each as an array of properties/segments.
+Return an array of all variables, each as an array of properties/segments.
+Return an array of all variables without their properties.
+Return an array of all variables without their properties.
+AbstractOptionaloriginalOptionalstackStatic OptionalprepareOptional override for formatting stack traces
+StaticstackProtectedupdateStaticcaptureStaticisOptionaloriginalOptionalstackStatic OptionalprepareOptional override for formatting stack traces
+StaticstackProtectedupdateStaticcaptureStaticisOptionaloriginalOptionalstackStatic OptionalprepareOptional override for formatting stack traces
+StaticstackProtectedupdateStaticcaptureStaticisProtectedtokenizerOptionalfile: stringAbstractOptionaloriginalOptionalstackStatic OptionalprepareOptional override for formatting stack traces
+StaticstackProtectedupdateStaticcaptureStaticisOptionaloriginalOptionalstackStatic OptionalprepareOptional override for formatting stack traces
+StaticstackProtectedupdateStaticcaptureStaticisA variable's segments and location, which can be coerced to a string.
+Return this variable's segments as an array, possibly with nested arrays for nested paths.
+Provide parent access in child block by +{{ block.super }}
+AbstractOptionalfile: stringOptionalfile: stringvalue expression with optional filters +e.g. +{% assign foo="bar" | append: "coo" %}
+Optionalfile: stringOptionalvalue: ValueTokenOptionalfile: stringOptionalfile: stringLiquidTagToken is different from TagToken by not having delimiters {% or %}
Optionalfile: stringOptionalfile: stringOptionalsync: booleanOptionalcurrentFile: stringOptionalfile: stringOptionalfile: stringOptionalfile: stringOptionalfile: stringOptionalfile: stringOptionalfile: stringAbstractStatically analyze a template and report variable usage.
+Statically analyze a template and report variable usage.
+
+
+
+
+
+
A simple, expressive and safe Shopify / GitHub Pages compatible template engine in pure JavaScript. +The purpose of this repo is to provide a standard Liquid implementation for the JavaScript community so that Jekyll sites, GitHub Pages and Shopify templates can be ported to Node.js without pain.
+
Basically there're two types of Liquid syntax: tags enclosed by {% %} and outputs enclosed by {{ }}. A Liquid template looks like:
{% if username %}
+ {{ username | append: ", welcome to LiquidJS!" | capitalize }}
+{% endif %}
+A live demo is also available and here's a quick tutorial for Liquid syntax.
+Install from npm in Node.js:
+npm install liquidjs
+Or use the UMD bundle from jsDelivr:
+<script src="https://cdn.jsdelivr.net/npm/liquidjs/dist/liquid.browser.min.js"></script>
+Or render directly from CLI using npx:
+npx liquidjs --template 'Hello, {{ name }}!' --context '{"name": "Snake"}'
+For more details, refer to the Setup Guide.
+Feel free to create a PR or contact me to add your use case into this list!
+If you personally love LiquidJS or it's benefiting your business, please consider financially support us via GitHub Sponsors. Special thanks to our sponsors!
+ +Opensense |
+ Eleventy |
+ Peter deHaan |
+ Touchless |
+ Dropkiq |
+ Dailycontributors |
+ Serkan Holat |
+
amit777 |
+ Khaled Salem |
+ Sentry |
+ Checkout Blocks |
+ Customer IO |
+ Emmanuel Cartelli |
+ Microsoft |
+
PakStyle.pk |
+ Syntax Podcast |
+ Cartelli Emmanuel |
+ EscortA.com |
+ Chudovo |
+
Want to contribute? see Contribution Guidelines. Thanks goes to these wonderful people:
+ + + +Optionalcontainscheck if file is contained in root, always return true by default. Warning: not setting this could expose path traversal vulnerabilities.
Optionaldirnamerequired for relative path resolving
+check if a file exists asynchronously
+check if a file exists synchronously
+Optionalfallbackfallback file for lookup failure
+read a file asynchronously
+read a file synchronously
+resolve a file against directory, for given ext option
Optionalsepdefaults to "/"
+OptionalcacheWhether or not to cache resolved templates. Defaults to false.
OptionalcatchCatch all errors instead of exit upon one. Please note that render errors won't be reached when parse fails.
+OptionaldateDefault date format to use if the date filter doesn't include a format. Defaults to %A, %B %-e, %Y at %-l:%M %P %z.
OptionaldynamicIf set, treat the filepath parameter in {%include filepath %} and {%layout filepath%} as a variable, otherwise as a literal value. Defaults to true.
OptionalextnameAdd a extname (if filepath doesn't include one) before template file lookup. Eg: setting to ".html" will allow including file by basename. Defaults to "".
Optionalfsfs is used to override the default file-system module with a custom implementation.
Optionalglobalsthe global scope passed down to all partial and layout templates, i.e. templates included by include, layout and render tags.
OptionalgreedyWhether trim*Left/trim*Right is greedy. When set to true, all consecutive blank characters including \n will be trimmed regardless of line breaks. Defaults to true.
OptionaljekyllUse jekyll style include, pass parameters to include variable of current scope. Defaults to false.
OptionaljekyllUse jekyll style where filter, enables array item match. Defaults to false.
OptionaljsUse JavaScript Truthiness. Defaults to false.
OptionalkeepWhether or not to keep value type when writing the Output, not working for streamed rendering. Defaults to false.
OptionalkeykeyValue separator
+OptionallayoutsA directory or an array of directories from where to resolve layout templates. If it's an array, the files are looked up in the order they occur in the array. Defaults to root
OptionallenientModifies the behavior of strictVariables. If set, a single undefined variable will not cause an exception in the context of the if/elsif/unless tag and the default filter. Instead, it will evaluate to false and null, respectively. Irrelevant if strictVariables is not set. Defaults to false. *
OptionallocaleDefault locale, will be used by date filter. Defaults to system locale.
+OptionalmemoryFor DoS handling, limit new objects creation, including array concat/join/strftime, etc. A typical PC can handle 1e9 (1G) memory without issue.
+OptionaloperatorsAn object of operators for conditional statements. Defaults to the regular Liquid operators.
+OptionalorderedRespect parameter order when using filters like "for ... reversed limit", Defaults to false.
OptionaloutputThe left delimiter for liquid outputs. *
+OptionaloutputThe right delimiter for liquid outputs. *
+OptionaloutputDefault escape filter applied to output values, when set, you'll have to add | raw for values don't need to be escaped. Defaults to undefined.
OptionalownHide scope variables from prototypes, useful when you're passing a not sanitized object into LiquidJS or need to hide prototypes from templates.
+OptionalparseFor DoS handling, limit total length of templates parsed in one parse() call. A typical PC can handle 1e8 (100M) characters without issues.
OptionalpartialsA directory or an array of directories from where to resolve included templates. If it's an array, the files are looked up in the order they occur in the array. Defaults to root
OptionalpreserveWhether input strings to date filter preserve the given timezone *
+OptionalrelativeAllow refer to layouts/partials by relative pathname. To avoid arbitrary filesystem read, paths been referenced also need to be within corresponding root, partials, layouts. Defaults to true.
OptionalrenderFor DoS handling, limit total time (in ms) for each render() call.
OptionalrootA directory or an array of directories from where to resolve layout and include templates, and the filename passed to .renderFile(). If it's an array, the files are looked up in the order they occur in the array. Defaults to ["."]
OptionalstrictWhether or not to assert filter existence. If set to false, undefined filters will be skipped. Otherwise, undefined filters will cause an exception. Defaults to false.
OptionalstrictWhether or not to assert variable existence. If set to false, undefined variables will be rendered as empty string. Otherwise, undefined variables will cause an exception. Defaults to false.
OptionaltagThe left delimiter for liquid tags. *
+OptionaltagThe right delimiter for liquid tags. *
+OptionaltemplatesRender from in-memory templates mapping instead of file system. File system related options like fs, 'root', and relativeReference will be ignored when templates is specified.
OptionaltimezoneJavaScript timezone name or timezoneOffset for date filter, default to local time. That means if you're in Australia (UTC+10), it'll default to -600 or Australia/Lindeman
OptionaltrimSimilar to trimOutputRight, whereas the \n is exclusive. Defaults to false. See Whitespace Control for details.
OptionaltrimStrip blank characters (including , \t, and \r) from the right of values ({{ }}) until \n (inclusive). Defaults to false.
OptionaltrimSimilar to trimTagRight, whereas the \n is exclusive. Defaults to false. See Whitespace Control for details.
OptionaltrimStrip blank characters (including , \t, and \r) from the right of tags ({% %}) until \n (inclusive). Defaults to false.
Scope information used when analyzing partial templates.
+If true, names in scope will be added to a new, isolated scope before
+analyzing any child templates, without access to the parent template's scope.
The name of the partial template. We need this to make sure we only analyze +each template once.
+A list of names that will be in scope for the child template.
+If an item is a [string, Argument] tuple, the string is considered an alias +for the argument.
+The result of calling analyze() or analyzeSync().
Variables that are not in scope. These could be a "global" variables that are +expected to be provided by the application developer, or possible mistakes +from the template author.
+If a variable is referenced before and after assignment, you should expect
+that variable to be included in globals, variables and locals, each with
+a different location.
Template variables that are added to the template local scope using tags like
+assign, capture or increment.
All variables, whether they are in scope or not. Including references to names
+such as forloop from the for tag.
OptionalargumentsOptionalblockOptionalchildrenOptionallocalOptionalpartialRest...args: [] | [undefined]OptionalreturnOptionalvalue: anyOptionalthrowOptionale: anyRest...args: [] | [TNext]OptionalreturnOptionalvalue: TReturn | PromiseLike<TReturn>OptionalthrowOptionale: anyReadonlyBYTES_The size in bytes of each element in the array.
+Readonly[toReadonlybufferThe ArrayBuffer instance referenced by the array.
+ReadonlybyteThe length in bytes of the array.
+ReadonlybyteThe offset in bytes of the array.
+ReadonlylengthThe length of the array.
+Compares buf with target and returns a number indicating whether bufcomes before, after, or is the same as target in sort order.
+Comparison is based on the actual sequence of bytes in each Buffer.
0 is returned if target is the same as buf1 is returned if target should come beforebuf when sorted.-1 is returned if target should come afterbuf when sorted.import { Buffer } from 'node:buffer';
const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('BCD');
const buf3 = Buffer.from('ABCD');
console.log(buf1.compare(buf1));
// Prints: 0
console.log(buf1.compare(buf2));
// Prints: -1
console.log(buf1.compare(buf3));
// Prints: -1
console.log(buf2.compare(buf1));
// Prints: 1
console.log(buf2.compare(buf3));
// Prints: 1
console.log([buf1, buf2, buf3].sort(Buffer.compare));
// Prints: [ <Buffer 41 42 43>, <Buffer 41 42 43 44>, <Buffer 42 43 44> ]
// (This result is equal to: [buf1, buf3, buf2].)
+The optional targetStart, targetEnd, sourceStart, and sourceEnd arguments can be used to limit the comparison to specific ranges within target and buf respectively.
import { Buffer } from 'node:buffer';
const buf1 = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8, 9]);
const buf2 = Buffer.from([5, 6, 7, 8, 9, 1, 2, 3, 4]);
console.log(buf1.compare(buf2, 5, 9, 0, 4));
// Prints: 0
console.log(buf1.compare(buf2, 0, 6, 4));
// Prints: -1
console.log(buf1.compare(buf2, 5, 6, 5));
// Prints: 1
+ERR_OUT_OF_RANGE is thrown if targetStart < 0, sourceStart < 0, targetEnd > target.byteLength, or sourceEnd > source.byteLength.
A Buffer or Uint8Array with which to compare buf.
OptionaltargetStart: numberThe offset within target at which to begin comparison.
OptionaltargetEnd: numberThe offset within target at which to end comparison (not inclusive).
OptionalsourceStart: numberThe offset within buf at which to begin comparison.
OptionalsourceEnd: numberThe offset within buf at which to end comparison (not inclusive).
Copies data from a region of buf to a region in target, even if the targetmemory region overlaps with buf.
TypedArray.prototype.set() performs the same operation, and is available
+for all TypedArrays, including Node.js Buffers, although it takes
+different function arguments.
import { Buffer } from 'node:buffer';
// Create two `Buffer` instances.
const buf1 = Buffer.allocUnsafe(26);
const buf2 = Buffer.allocUnsafe(26).fill('!');
for (let i = 0; i < 26; i++) {
// 97 is the decimal ASCII value for 'a'.
buf1[i] = i + 97;
}
// Copy `buf1` bytes 16 through 19 into `buf2` starting at byte 8 of `buf2`.
buf1.copy(buf2, 8, 16, 20);
// This is equivalent to:
// buf2.set(buf1.subarray(16, 20), 8);
console.log(buf2.toString('ascii', 0, 25));
// Prints: !!!!!!!!qrst!!!!!!!!!!!!!
+import { Buffer } from 'node:buffer';
// Create a `Buffer` and copy data from one region to an overlapping region
// within the same `Buffer`.
const buf = Buffer.allocUnsafe(26);
for (let i = 0; i < 26; i++) {
// 97 is the decimal ASCII value for 'a'.
buf[i] = i + 97;
}
buf.copy(buf, 0, 4, 10);
console.log(buf.toString());
// Prints: efghijghijklmnopqrstuvwxyz
+A Buffer or Uint8Array to copy into.
OptionaltargetStart: numberThe offset within target at which to begin writing.
OptionalsourceStart: numberThe offset within buf from which to begin copying.
OptionalsourceEnd: numberThe offset within buf at which to stop copying (not inclusive).
The number of bytes copied.
+Returns the this object after copying a section of the array identified by start and end +to the same array starting at position target
+If target is negative, it is treated as length+target where length is the +length of the array.
+If start is negative, it is treated as length+start. If end is negative, it +is treated as length+end.
+Optionalend: numberIf not specified, length of the this object is used as its default value.
+Returns an array of key, value pairs for every entry in the array
+Returns true if both buf and otherBuffer have exactly the same bytes,false otherwise. Equivalent to buf.compare(otherBuffer) === 0.
import { Buffer } from 'node:buffer';
const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('414243', 'hex');
const buf3 = Buffer.from('ABCD');
console.log(buf1.equals(buf2));
// Prints: true
console.log(buf1.equals(buf3));
// Prints: false
+A Buffer or Uint8Array with which to compare buf.
Determines whether all the members of an array satisfy the specified test.
+A function that accepts up to three arguments. The every method calls +the predicate function for each element in the array until the predicate returns a value +which is coercible to the Boolean value false, or until the end of the array.
+OptionalthisArg: anyAn object to which the this keyword can refer in the predicate function. +If thisArg is omitted, undefined is used as the this value.
+Fills buf with the specified value. If the offset and end are not given,
+the entire buf will be filled:
import { Buffer } from 'node:buffer';
// Fill a `Buffer` with the ASCII character 'h'.
const b = Buffer.allocUnsafe(50).fill('h');
console.log(b.toString());
// Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
// Fill a buffer with empty string
const c = Buffer.allocUnsafe(5).fill('');
console.log(c.fill(''));
// Prints: <Buffer 00 00 00 00 00>
+value is coerced to a uint32 value if it is not a string, Buffer, or
+integer. If the resulting integer is greater than 255 (decimal), buf will be
+filled with value & 255.
If the final write of a fill() operation falls on a multi-byte character,
+then only the bytes of that character that fit into buf are written:
import { Buffer } from 'node:buffer';
// Fill a `Buffer` with character that takes up two bytes in UTF-8.
console.log(Buffer.allocUnsafe(5).fill('\u0222'));
// Prints: <Buffer c8 a2 c8 a2 c8>
+If value contains invalid characters, it is truncated; if no valid
+fill data remains, an exception is thrown:
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(5);
console.log(buf.fill('a'));
// Prints: <Buffer 61 61 61 61 61>
console.log(buf.fill('aazz', 'hex'));
// Prints: <Buffer aa aa aa aa aa>
console.log(buf.fill('zz', 'hex'));
// Throws an exception.
+The value with which to fill buf. Empty value (string, Uint8Array, Buffer) is coerced to 0.
Optionaloffset: numberNumber of bytes to skip before starting to fill buf.
Optionalend: numberWhere to stop filling buf (not inclusive).
Optionalencoding: BufferEncodingThe encoding for value if value is a string.
A reference to buf.
Returns the elements of an array that meet the condition specified in a callback function.
+A function that accepts up to three arguments. The filter method calls +the predicate function one time for each element in the array.
+OptionalthisArg: anyAn object to which the this keyword can refer in the predicate function. +If thisArg is omitted, undefined is used as the this value.
+Returns the value of the first element in the array where predicate is true, and undefined +otherwise.
+find calls predicate once for each element of the array, in ascending +order, until it finds one where predicate returns true. If such an element is found, find +immediately returns that element value. Otherwise, find returns undefined.
+OptionalthisArg: anyIf provided, it will be used as the this value for each invocation of +predicate. If it is not provided, undefined is used instead.
+Returns the index of the first element in the array where predicate is true, and -1 +otherwise.
+find calls predicate once for each element of the array, in ascending +order, until it finds one where predicate returns true. If such an element is found, +findIndex immediately returns that element index. Otherwise, findIndex returns -1.
+OptionalthisArg: anyIf provided, it will be used as the this value for each invocation of +predicate. If it is not provided, undefined is used instead.
+Performs the specified action for each element in an array.
+A function that accepts up to three arguments. forEach calls the +callbackfn function one time for each element in the array.
+OptionalthisArg: anyAn object to which the this keyword can refer in the callbackfn function. +If thisArg is omitted, undefined is used as the this value.
+Equivalent to buf.indexOf() !== -1.
import { Buffer } from 'node:buffer';
const buf = Buffer.from('this is a buffer');
console.log(buf.includes('this'));
// Prints: true
console.log(buf.includes('is'));
// Prints: true
console.log(buf.includes(Buffer.from('a buffer')));
// Prints: true
console.log(buf.includes(97));
// Prints: true (97 is the decimal ASCII value for 'a')
console.log(buf.includes(Buffer.from('a buffer example')));
// Prints: false
console.log(buf.includes(Buffer.from('a buffer example').slice(0, 8)));
// Prints: true
console.log(buf.includes('this', 4));
// Prints: false
+What to search for.
+OptionalbyteOffset: numberWhere to begin searching in buf. If negative, then offset is calculated from the end of buf.
Optionalencoding: BufferEncodingIf value is a string, this is its encoding.
true if value was found in buf, false otherwise.
If value is:
value is interpreted according to the character encoding in encoding.Buffer or Uint8Array, value will be used in its entirety.
+To compare a partial Buffer, use buf.subarray.value will be interpreted as an unsigned 8-bit integer
+value between 0 and 255.import { Buffer } from 'node:buffer';
const buf = Buffer.from('this is a buffer');
console.log(buf.indexOf('this'));
// Prints: 0
console.log(buf.indexOf('is'));
// Prints: 2
console.log(buf.indexOf(Buffer.from('a buffer')));
// Prints: 8
console.log(buf.indexOf(97));
// Prints: 8 (97 is the decimal ASCII value for 'a')
console.log(buf.indexOf(Buffer.from('a buffer example')));
// Prints: -1
console.log(buf.indexOf(Buffer.from('a buffer example').slice(0, 8)));
// Prints: 8
const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');
console.log(utf16Buffer.indexOf('\u03a3', 0, 'utf16le'));
// Prints: 4
console.log(utf16Buffer.indexOf('\u03a3', -4, 'utf16le'));
// Prints: 6
+If value is not a string, number, or Buffer, this method will throw a TypeError. If value is a number, it will be coerced to a valid byte value,
+an integer between 0 and 255.
If byteOffset is not a number, it will be coerced to a number. If the result
+of coercion is NaN or 0, then the entire buffer will be searched. This
+behavior matches String.prototype.indexOf().
import { Buffer } from 'node:buffer';
const b = Buffer.from('abcdef');
// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.indexOf(99.9));
console.log(b.indexOf(256 + 99));
// Passing a byteOffset that coerces to NaN or 0.
// Prints: 1, searching the whole buffer.
console.log(b.indexOf('b', undefined));
console.log(b.indexOf('b', {}));
console.log(b.indexOf('b', null));
console.log(b.indexOf('b', []));
+If value is an empty string or empty Buffer and byteOffset is less
+than buf.length, byteOffset will be returned. If value is empty andbyteOffset is at least buf.length, buf.length will be returned.
What to search for.
+OptionalbyteOffset: numberWhere to begin searching in buf. If negative, then offset is calculated from the end of buf.
Optionalencoding: BufferEncodingIf value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf.
The index of the first occurrence of value in buf, or -1 if buf does not contain value.
Adds all the elements of an array separated by the specified separator string.
+Optionalseparator: stringA string used to separate one element of an array from the next in the +resulting String. If omitted, the array elements are separated with a comma.
+Returns an list of keys in the array
+Identical to buf.indexOf(), except the last occurrence of value is found
+rather than the first occurrence.
import { Buffer } from 'node:buffer';
const buf = Buffer.from('this buffer is a buffer');
console.log(buf.lastIndexOf('this'));
// Prints: 0
console.log(buf.lastIndexOf('buffer'));
// Prints: 17
console.log(buf.lastIndexOf(Buffer.from('buffer')));
// Prints: 17
console.log(buf.lastIndexOf(97));
// Prints: 15 (97 is the decimal ASCII value for 'a')
console.log(buf.lastIndexOf(Buffer.from('yolo')));
// Prints: -1
console.log(buf.lastIndexOf('buffer', 5));
// Prints: 5
console.log(buf.lastIndexOf('buffer', 4));
// Prints: -1
const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');
console.log(utf16Buffer.lastIndexOf('\u03a3', undefined, 'utf16le'));
// Prints: 6
console.log(utf16Buffer.lastIndexOf('\u03a3', -5, 'utf16le'));
// Prints: 4
+If value is not a string, number, or Buffer, this method will throw a TypeError. If value is a number, it will be coerced to a valid byte value,
+an integer between 0 and 255.
If byteOffset is not a number, it will be coerced to a number. Any arguments
+that coerce to NaN, like {} or undefined, will search the whole buffer.
+This behavior matches String.prototype.lastIndexOf().
import { Buffer } from 'node:buffer';
const b = Buffer.from('abcdef');
// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.lastIndexOf(99.9));
console.log(b.lastIndexOf(256 + 99));
// Passing a byteOffset that coerces to NaN.
// Prints: 1, searching the whole buffer.
console.log(b.lastIndexOf('b', undefined));
console.log(b.lastIndexOf('b', {}));
// Passing a byteOffset that coerces to 0.
// Prints: -1, equivalent to passing 0.
console.log(b.lastIndexOf('b', null));
console.log(b.lastIndexOf('b', []));
+If value is an empty string or empty Buffer, byteOffset will be returned.
What to search for.
+OptionalbyteOffset: numberWhere to begin searching in buf. If negative, then offset is calculated from the end of buf.
Optionalencoding: BufferEncodingIf value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf.
The index of the last occurrence of value in buf, or -1 if buf does not contain value.
Calls a defined callback function on each element of an array, and returns an array that +contains the results.
+A function that accepts up to three arguments. The map method calls the +callbackfn function one time for each element in the array.
+OptionalthisArg: anyAn object to which the this keyword can refer in the callbackfn function. +If thisArg is omitted, undefined is used as the this value.
+Reads a signed, big-endian 64-bit integer from buf at the specified offset.
Integers read from a Buffer are interpreted as two's complement signed
+values.
Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Reads a signed, little-endian 64-bit integer from buf at the specifiedoffset.
Integers read from a Buffer are interpreted as two's complement signed
+values.
Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Reads an unsigned, big-endian 64-bit integer from buf at the specifiedoffset.
This function is also available under the readBigUint64BE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);
console.log(buf.readBigUInt64BE(0));
// Prints: 4294967295n
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Reads an unsigned, little-endian 64-bit integer from buf at the specifiedoffset.
This function is also available under the readBigUint64LE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);
console.log(buf.readBigUInt64LE(0));
// Prints: 18446744069414584320n
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Reads a 64-bit, big-endian double from buf at the specified offset.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);
console.log(buf.readDoubleBE(0));
// Prints: 8.20788039913184e-304
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8.
Reads a 64-bit, little-endian double from buf at the specified offset.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);
console.log(buf.readDoubleLE(0));
// Prints: 5.447603722011605e-270
console.log(buf.readDoubleLE(1));
// Throws ERR_OUT_OF_RANGE.
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8.
Reads a 32-bit, big-endian float from buf at the specified offset.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([1, 2, 3, 4]);
console.log(buf.readFloatBE(0));
// Prints: 2.387939260590663e-38
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Reads a 32-bit, little-endian float from buf at the specified offset.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([1, 2, 3, 4]);
console.log(buf.readFloatLE(0));
// Prints: 1.539989614439558e-36
console.log(buf.readFloatLE(1));
// Throws ERR_OUT_OF_RANGE.
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Reads a signed, big-endian 16-bit integer from buf at the specified offset.
Integers read from a Buffer are interpreted as two's complement signed values.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0, 5]);
console.log(buf.readInt16BE(0));
// Prints: 5
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Reads a signed, little-endian 16-bit integer from buf at the specifiedoffset.
Integers read from a Buffer are interpreted as two's complement signed values.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0, 5]);
console.log(buf.readInt16LE(0));
// Prints: 1280
console.log(buf.readInt16LE(1));
// Throws ERR_OUT_OF_RANGE.
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Reads a signed, big-endian 32-bit integer from buf at the specified offset.
Integers read from a Buffer are interpreted as two's complement signed values.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0, 0, 0, 5]);
console.log(buf.readInt32BE(0));
// Prints: 5
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Reads a signed, little-endian 32-bit integer from buf at the specifiedoffset.
Integers read from a Buffer are interpreted as two's complement signed values.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0, 0, 0, 5]);
console.log(buf.readInt32LE(0));
// Prints: 83886080
console.log(buf.readInt32LE(1));
// Throws ERR_OUT_OF_RANGE.
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Reads a signed 8-bit integer from buf at the specified offset.
Integers read from a Buffer are interpreted as two's complement signed values.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([-1, 5]);
console.log(buf.readInt8(0));
// Prints: -1
console.log(buf.readInt8(1));
// Prints: 5
console.log(buf.readInt8(2));
// Throws ERR_OUT_OF_RANGE.
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1.
Reads byteLength number of bytes from buf at the specified offset and interprets the result as a big-endian, two's complement signed value
+supporting up to 48 bits of accuracy.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);
console.log(buf.readIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.
console.log(buf.readIntBE(1, 0).toString(16));
// Throws ERR_OUT_OF_RANGE.
+Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Reads byteLength number of bytes from buf at the specified offset and interprets the result as a little-endian, two's complement signed value
+supporting up to 48 bits of accuracy.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);
console.log(buf.readIntLE(0, 6).toString(16));
// Prints: -546f87a9cbee
+Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Reads an unsigned, big-endian 16-bit integer from buf at the specifiedoffset.
This function is also available under the readUint16BE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x12, 0x34, 0x56]);
console.log(buf.readUInt16BE(0).toString(16));
// Prints: 1234
console.log(buf.readUInt16BE(1).toString(16));
// Prints: 3456
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Reads an unsigned, little-endian 16-bit integer from buf at the specified offset.
This function is also available under the readUint16LE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x12, 0x34, 0x56]);
console.log(buf.readUInt16LE(0).toString(16));
// Prints: 3412
console.log(buf.readUInt16LE(1).toString(16));
// Prints: 5634
console.log(buf.readUInt16LE(2).toString(16));
// Throws ERR_OUT_OF_RANGE.
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Reads an unsigned, big-endian 32-bit integer from buf at the specifiedoffset.
This function is also available under the readUint32BE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);
console.log(buf.readUInt32BE(0).toString(16));
// Prints: 12345678
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Reads an unsigned, little-endian 32-bit integer from buf at the specifiedoffset.
This function is also available under the readUint32LE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);
console.log(buf.readUInt32LE(0).toString(16));
// Prints: 78563412
console.log(buf.readUInt32LE(1).toString(16));
// Throws ERR_OUT_OF_RANGE.
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Reads an unsigned 8-bit integer from buf at the specified offset.
This function is also available under the readUint8 alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([1, -2]);
console.log(buf.readUInt8(0));
// Prints: 1
console.log(buf.readUInt8(1));
// Prints: 254
console.log(buf.readUInt8(2));
// Throws ERR_OUT_OF_RANGE.
+Optionaloffset: numberNumber of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1.
Reads byteLength number of bytes from buf at the specified offset and interprets the result as an unsigned big-endian integer supporting
+up to 48 bits of accuracy.
This function is also available under the readUintBE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);
console.log(buf.readUIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readUIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.
+Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Reads byteLength number of bytes from buf at the specified offset and interprets the result as an unsigned, little-endian integer supporting
+up to 48 bits of accuracy.
This function is also available under the readUintLE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);
console.log(buf.readUIntLE(0, 6).toString(16));
// Prints: ab9078563412
+Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Calls the specified callback function for all the elements in an array. The return value of +the callback function is the accumulated result, and is provided as an argument in the next +call to the callback function.
+A function that accepts up to four arguments. The reduce method calls the +callbackfn function one time for each element in the array.
+Calls the specified callback function for all the elements in an array. The return value of +the callback function is the accumulated result, and is provided as an argument in the next +call to the callback function.
+A function that accepts up to four arguments. The reduce method calls the +callbackfn function one time for each element in the array.
+If initialValue is specified, it is used as the initial value to start +the accumulation. The first call to the callbackfn function provides this value as an argument +instead of an array value.
+Calls the specified callback function for all the elements in an array, in descending order. +The return value of the callback function is the accumulated result, and is provided as an +argument in the next call to the callback function.
+A function that accepts up to four arguments. The reduceRight method calls +the callbackfn function one time for each element in the array.
+Calls the specified callback function for all the elements in an array, in descending order. +The return value of the callback function is the accumulated result, and is provided as an +argument in the next call to the callback function.
+A function that accepts up to four arguments. The reduceRight method calls +the callbackfn function one time for each element in the array.
+If initialValue is specified, it is used as the initial value to start +the accumulation. The first call to the callbackfn function provides this value as an argument +instead of an array value.
+Sets a value or an array of values.
+A typed or untyped array of values to set.
+Optionaloffset: numberThe index in the current array at which the values are to be written.
+Returns a new Buffer that references the same memory as the original, but
+offset and cropped by the start and end indices.
This method is not compatible with the Uint8Array.prototype.slice(),
+which is a superclass of Buffer. To copy the slice, useUint8Array.prototype.slice().
import { Buffer } from 'node:buffer';
const buf = Buffer.from('buffer');
const copiedBuf = Uint8Array.prototype.slice.call(buf);
copiedBuf[0]++;
console.log(copiedBuf.toString());
// Prints: cuffer
console.log(buf.toString());
// Prints: buffer
// With buf.slice(), the original buffer is modified.
const notReallyCopiedBuf = buf.slice();
notReallyCopiedBuf[0]++;
console.log(notReallyCopiedBuf.toString());
// Prints: cuffer
console.log(buf.toString());
// Also prints: cuffer (!)
+Optionalstart: numberWhere the new Buffer will start.
Optionalend: numberWhere the new Buffer will end (not inclusive).
Determines whether the specified callback function returns true for any element of an array.
+A function that accepts up to three arguments. The some method calls +the predicate function for each element in the array until the predicate returns a value +which is coercible to the Boolean value true, or until the end of the array.
+OptionalthisArg: anyAn object to which the this keyword can refer in the predicate function. +If thisArg is omitted, undefined is used as the this value.
+Sorts an array.
+OptionalcompareFn: ((a: number, b: number) => number)Function used to determine the order of the elements. It is expected to return +a negative value if first argument is less than second argument, zero if they're equal and a positive +value otherwise. If omitted, the elements are sorted in ascending order.
+[11,2,22,1].sort((a, b) => a - b)
+Returns a new Buffer that references the same memory as the original, but
+offset and cropped by the start and end indices.
Specifying end greater than buf.length will return the same result as
+that of end equal to buf.length.
This method is inherited from TypedArray.prototype.subarray().
Modifying the new Buffer slice will modify the memory in the original Bufferbecause the allocated memory of the two objects overlap.
import { Buffer } from 'node:buffer';
// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte
// from the original `Buffer`.
const buf1 = Buffer.allocUnsafe(26);
for (let i = 0; i < 26; i++) {
// 97 is the decimal ASCII value for 'a'.
buf1[i] = i + 97;
}
const buf2 = buf1.subarray(0, 3);
console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: abc
buf1[0] = 33;
console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: !bc
+Specifying negative indexes causes the slice to be generated relative to the
+end of buf rather than the beginning.
import { Buffer } from 'node:buffer';
const buf = Buffer.from('buffer');
console.log(buf.subarray(-6, -1).toString());
// Prints: buffe
// (Equivalent to buf.subarray(0, 5).)
console.log(buf.subarray(-6, -2).toString());
// Prints: buff
// (Equivalent to buf.subarray(0, 4).)
console.log(buf.subarray(-5, -2).toString());
// Prints: uff
// (Equivalent to buf.subarray(1, 4).)
+Optionalstart: numberWhere the new Buffer will start.
Optionalend: numberWhere the new Buffer will end (not inclusive).
Interprets buf as an array of unsigned 16-bit integers and swaps the
+byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 2.
import { Buffer } from 'node:buffer';
const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);
console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>
buf1.swap16();
console.log(buf1);
// Prints: <Buffer 02 01 04 03 06 05 08 07>
const buf2 = Buffer.from([0x1, 0x2, 0x3]);
buf2.swap16();
// Throws ERR_INVALID_BUFFER_SIZE.
+One convenient use of buf.swap16() is to perform a fast in-place conversion
+between UTF-16 little-endian and UTF-16 big-endian:
import { Buffer } from 'node:buffer';
const buf = Buffer.from('This is little-endian UTF-16', 'utf16le');
buf.swap16(); // Convert to big-endian UTF-16 text.
+A reference to buf.
Interprets buf as an array of unsigned 32-bit integers and swaps the
+byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 4.
import { Buffer } from 'node:buffer';
const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);
console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>
buf1.swap32();
console.log(buf1);
// Prints: <Buffer 04 03 02 01 08 07 06 05>
const buf2 = Buffer.from([0x1, 0x2, 0x3]);
buf2.swap32();
// Throws ERR_INVALID_BUFFER_SIZE.
+A reference to buf.
Interprets buf as an array of 64-bit numbers and swaps byte order in-place.
+Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 8.
import { Buffer } from 'node:buffer';
const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);
console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>
buf1.swap64();
console.log(buf1);
// Prints: <Buffer 08 07 06 05 04 03 02 01>
const buf2 = Buffer.from([0x1, 0x2, 0x3]);
buf2.swap64();
// Throws ERR_INVALID_BUFFER_SIZE.
+A reference to buf.
Returns a JSON representation of buf. JSON.stringify() implicitly calls
+this function when stringifying a Buffer instance.
Buffer.from() accepts objects in the format returned from this method.
+In particular, Buffer.from(buf.toJSON()) works like Buffer.from(buf).
import { Buffer } from 'node:buffer';
const buf = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5]);
const json = JSON.stringify(buf);
console.log(json);
// Prints: {"type":"Buffer","data":[1,2,3,4,5]}
const copy = JSON.parse(json, (key, value) => {
return value && value.type === 'Buffer' ?
Buffer.from(value) :
value;
});
console.log(copy);
// Prints: <Buffer 01 02 03 04 05>
+Decodes buf to a string according to the specified character encoding inencoding. start and end may be passed to decode only a subset of buf.
If encoding is 'utf8' and a byte sequence in the input is not valid UTF-8,
+then each invalid byte is replaced with the replacement character U+FFFD.
The maximum length of a string instance (in UTF-16 code units) is available +as constants.MAX_STRING_LENGTH.
+import { Buffer } from 'node:buffer';
const buf1 = Buffer.allocUnsafe(26);
for (let i = 0; i < 26; i++) {
// 97 is the decimal ASCII value for 'a'.
buf1[i] = i + 97;
}
console.log(buf1.toString('utf8'));
// Prints: abcdefghijklmnopqrstuvwxyz
console.log(buf1.toString('utf8', 0, 5));
// Prints: abcde
const buf2 = Buffer.from('tést');
console.log(buf2.toString('hex'));
// Prints: 74c3a97374
console.log(buf2.toString('utf8', 0, 3));
// Prints: té
console.log(buf2.toString(undefined, 0, 3));
// Prints: té
+Optionalencoding: BufferEncodingThe character encoding to use.
+Optionalstart: numberThe byte offset to start decoding at.
+Optionalend: numberThe byte offset to stop decoding at (not inclusive).
+Returns an list of values in the array
+Writes string to buf at offset according to the character encoding inencoding. The length parameter is the number of bytes to write. If buf did
+not contain enough space to fit the entire string, only part of string will be
+written. However, partially encoded characters will not be written.
import { Buffer } from 'node:buffer';
const buf = Buffer.alloc(256);
const len = buf.write('\u00bd + \u00bc = \u00be', 0);
console.log(`${len} bytes: ${buf.toString('utf8', 0, len)}`);
// Prints: 12 bytes: ½ + ¼ = ¾
const buffer = Buffer.alloc(10);
const length = buffer.write('abcd', 8);
console.log(`${length} bytes: ${buffer.toString('utf8', 8, 10)}`);
// Prints: 2 bytes : ab
+String to write to buf.
Optionalencoding: BufferEncodingThe character encoding of string.
Number of bytes written.
+Optionalencoding: BufferEncodingOptionalencoding: BufferEncodingWrites value to buf at the specified offset as big-endian.
value is interpreted and written as a two's complement signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(8);
buf.writeBigInt64BE(0x0102030405060708n, 0);
console.log(buf);
// Prints: <Buffer 01 02 03 04 05 06 07 08>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
offset plus the number of bytes written.
Writes value to buf at the specified offset as little-endian.
value is interpreted and written as a two's complement signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(8);
buf.writeBigInt64LE(0x0102030405060708n, 0);
console.log(buf);
// Prints: <Buffer 08 07 06 05 04 03 02 01>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
offset plus the number of bytes written.
Writes value to buf at the specified offset as big-endian.
This function is also available under the writeBigUint64BE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(8);
buf.writeBigUInt64BE(0xdecafafecacefaden, 0);
console.log(buf);
// Prints: <Buffer de ca fa fe ca ce fa de>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
offset plus the number of bytes written.
Writes value to buf at the specified offset as little-endian
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(8);
buf.writeBigUInt64LE(0xdecafafecacefaden, 0);
console.log(buf);
// Prints: <Buffer de fa ce ca fe fa ca de>
+This function is also available under the writeBigUint64LE alias.
Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
offset plus the number of bytes written.
Writes value to buf at the specified offset as big-endian. The value must be a JavaScript number. Behavior is undefined when value is anything
+other than a JavaScript number.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(8);
buf.writeDoubleBE(123.456, 0);
console.log(buf);
// Prints: <Buffer 40 5e dd 2f 1a 9f be 77>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8.
offset plus the number of bytes written.
Writes value to buf at the specified offset as little-endian. The value must be a JavaScript number. Behavior is undefined when value is anything
+other than a JavaScript number.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(8);
buf.writeDoubleLE(123.456, 0);
console.log(buf);
// Prints: <Buffer 77 be 9f 1a 2f dd 5e 40>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8.
offset plus the number of bytes written.
Writes value to buf at the specified offset as big-endian. Behavior is
+undefined when value is anything other than a JavaScript number.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeFloatBE(0xcafebabe, 0);
console.log(buf);
// Prints: <Buffer 4f 4a fe bb>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
offset plus the number of bytes written.
Writes value to buf at the specified offset as little-endian. Behavior is
+undefined when value is anything other than a JavaScript number.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeFloatLE(0xcafebabe, 0);
console.log(buf);
// Prints: <Buffer bb fe 4a 4f>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
offset plus the number of bytes written.
Writes value to buf at the specified offset as big-endian. The value must be a valid signed 16-bit integer. Behavior is undefined when value is
+anything other than a signed 16-bit integer.
The value is interpreted and written as a two's complement signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(2);
buf.writeInt16BE(0x0102, 0);
console.log(buf);
// Prints: <Buffer 01 02>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
offset plus the number of bytes written.
Writes value to buf at the specified offset as little-endian. The value must be a valid signed 16-bit integer. Behavior is undefined when value is
+anything other than a signed 16-bit integer.
The value is interpreted and written as a two's complement signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(2);
buf.writeInt16LE(0x0304, 0);
console.log(buf);
// Prints: <Buffer 04 03>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
offset plus the number of bytes written.
Writes value to buf at the specified offset as big-endian. The value must be a valid signed 32-bit integer. Behavior is undefined when value is
+anything other than a signed 32-bit integer.
The value is interpreted and written as a two's complement signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeInt32BE(0x01020304, 0);
console.log(buf);
// Prints: <Buffer 01 02 03 04>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
offset plus the number of bytes written.
Writes value to buf at the specified offset as little-endian. The value must be a valid signed 32-bit integer. Behavior is undefined when value is
+anything other than a signed 32-bit integer.
The value is interpreted and written as a two's complement signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeInt32LE(0x05060708, 0);
console.log(buf);
// Prints: <Buffer 08 07 06 05>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
offset plus the number of bytes written.
Writes value to buf at the specified offset. value must be a valid
+signed 8-bit integer. Behavior is undefined when value is anything other than
+a signed 8-bit integer.
value is interpreted and written as a two's complement signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(2);
buf.writeInt8(2, 0);
buf.writeInt8(-2, 1);
console.log(buf);
// Prints: <Buffer 02 fe>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1.
offset plus the number of bytes written.
Writes byteLength bytes of value to buf at the specified offsetas big-endian. Supports up to 48 bits of accuracy. Behavior is undefined whenvalue is anything other than a
+signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(6);
buf.writeIntBE(0x1234567890ab, 0, 6);
console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>
+Number to be written to buf.
Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
Number of bytes to write. Must satisfy 0 < byteLength <= 6.
offset plus the number of bytes written.
Writes byteLength bytes of value to buf at the specified offsetas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined
+when value is anything other than a signed integer.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(6);
buf.writeIntLE(0x1234567890ab, 0, 6);
console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>
+Number to be written to buf.
Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
Number of bytes to write. Must satisfy 0 < byteLength <= 6.
offset plus the number of bytes written.
Writes value to buf at the specified offset as big-endian. The value must be a valid unsigned 16-bit integer. Behavior is undefined when valueis anything other than an
+unsigned 16-bit integer.
This function is also available under the writeUint16BE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeUInt16BE(0xdead, 0);
buf.writeUInt16BE(0xbeef, 2);
console.log(buf);
// Prints: <Buffer de ad be ef>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
offset plus the number of bytes written.
Writes value to buf at the specified offset as little-endian. The value must be a valid unsigned 16-bit integer. Behavior is undefined when value is
+anything other than an unsigned 16-bit integer.
This function is also available under the writeUint16LE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeUInt16LE(0xdead, 0);
buf.writeUInt16LE(0xbeef, 2);
console.log(buf);
// Prints: <Buffer ad de ef be>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
offset plus the number of bytes written.
Writes value to buf at the specified offset as big-endian. The value must be a valid unsigned 32-bit integer. Behavior is undefined when valueis anything other than an
+unsigned 32-bit integer.
This function is also available under the writeUint32BE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeUInt32BE(0xfeedface, 0);
console.log(buf);
// Prints: <Buffer fe ed fa ce>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
offset plus the number of bytes written.
Writes value to buf at the specified offset as little-endian. The value must be a valid unsigned 32-bit integer. Behavior is undefined when value is
+anything other than an unsigned 32-bit integer.
This function is also available under the writeUint32LE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeUInt32LE(0xfeedface, 0);
console.log(buf);
// Prints: <Buffer ce fa ed fe>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
offset plus the number of bytes written.
Writes value to buf at the specified offset. value must be a
+valid unsigned 8-bit integer. Behavior is undefined when value is anything
+other than an unsigned 8-bit integer.
This function is also available under the writeUint8 alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(4);
buf.writeUInt8(0x3, 0);
buf.writeUInt8(0x4, 1);
buf.writeUInt8(0x23, 2);
buf.writeUInt8(0x42, 3);
console.log(buf);
// Prints: <Buffer 03 04 23 42>
+Number to be written to buf.
Optionaloffset: numberNumber of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1.
offset plus the number of bytes written.
Writes byteLength bytes of value to buf at the specified offsetas big-endian. Supports up to 48 bits of accuracy. Behavior is undefined
+when value is anything other than an unsigned integer.
This function is also available under the writeUintBE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(6);
buf.writeUIntBE(0x1234567890ab, 0, 6);
console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>
+Number to be written to buf.
Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
Number of bytes to write. Must satisfy 0 < byteLength <= 6.
offset plus the number of bytes written.
Writes byteLength bytes of value to buf at the specified offsetas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined
+when value is anything other than an unsigned integer.
This function is also available under the writeUintLE alias.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(6);
buf.writeUIntLE(0x1234567890ab, 0, 6);
console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>
+Number to be written to buf.
Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
Number of bytes to write. Must satisfy 0 < byteLength <= 6.
offset plus the number of bytes written.
Raw data is stored in instances of the Buffer class. +A Buffer is similar to an array of integers but corresponds to a raw memory allocation outside the V8 heap. A Buffer cannot be resized. +Valid string encodings: 'ascii'|'utf8'|'utf16le'|'ucs2'(alias of 'utf16le')|'base64'|'base64url'|'binary'(deprecated)|'hex'
+Allocates a new buffer containing the given {str}.
+String to store in buffer.
+Optionalencoding: BufferEncodingencoding to use, optional. Default is 'utf8'
+Allocates a new buffer of {size} octets.
+count of octets to allocate.
+Allocates a new buffer containing the given {array} of octets.
+The octets to store.
+Produces a Buffer backed by the same allocated memory as +the given {ArrayBuffer}/{SharedArrayBuffer}.
+The ArrayBuffer with which to share memory.
+Allocates a new buffer containing the given {array} of octets.
+The octets to store.
+Copies the passed {buffer} data onto a new {Buffer} instance.
+The buffer to copy.
+This is the size (in bytes) of pre-allocated internal Buffer instances used
+for pooling. This value may be modified.
Allocates a new Buffer of size bytes. If fill is undefined, theBuffer will be zero-filled.
import { Buffer } from 'node:buffer';
const buf = Buffer.alloc(5);
console.log(buf);
// Prints: <Buffer 00 00 00 00 00>
+If size is larger than constants.MAX_LENGTH or smaller than 0, ERR_OUT_OF_RANGE is thrown.
If fill is specified, the allocated Buffer will be initialized by calling buf.fill(fill).
import { Buffer } from 'node:buffer';
const buf = Buffer.alloc(5, 'a');
console.log(buf);
// Prints: <Buffer 61 61 61 61 61>
+If both fill and encoding are specified, the allocated Buffer will be
+initialized by calling buf.fill(fill, encoding).
import { Buffer } from 'node:buffer';
const buf = Buffer.alloc(11, 'aGVsbG8gd29ybGQ=', 'base64');
console.log(buf);
// Prints: <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64>
+Calling Buffer.alloc() can be measurably slower than the alternative Buffer.allocUnsafe() but ensures that the newly created Buffer instance
+contents will never contain sensitive data from previous allocations, including
+data that might not have been allocated for Buffers.
A TypeError will be thrown if size is not a number.
The desired length of the new Buffer.
Optionalfill: string | number | Uint8ArrayA value to pre-fill the new Buffer with.
Optionalencoding: BufferEncodingIf fill is a string, this is its encoding.
Allocates a new Buffer of size bytes. If size is larger than constants.MAX_LENGTH or smaller than 0, ERR_OUT_OF_RANGE is thrown.
The underlying memory for Buffer instances created in this way is not
+initialized. The contents of the newly created Buffer are unknown and may contain sensitive data. Use Buffer.alloc() instead to initializeBuffer instances with zeroes.
import { Buffer } from 'node:buffer';
const buf = Buffer.allocUnsafe(10);
console.log(buf);
// Prints (contents may vary): <Buffer a0 8b 28 3f 01 00 00 00 50 32>
buf.fill(0);
console.log(buf);
// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00>
+A TypeError will be thrown if size is not a number.
The Buffer module pre-allocates an internal Buffer instance of
+size Buffer.poolSize that is used as a pool for the fast allocation of new Buffer instances created using Buffer.allocUnsafe(), Buffer.from(array),
+and Buffer.concat() only when size is less than Buffer.poolSize >>> 1 (floor of Buffer.poolSize divided by two).
Use of this pre-allocated internal memory pool is a key difference between
+calling Buffer.alloc(size, fill) vs. Buffer.allocUnsafe(size).fill(fill).
+Specifically, Buffer.alloc(size, fill) will never use the internal Bufferpool, while Buffer.allocUnsafe(size).fill(fill)will use the internalBuffer pool if size is less
+than or equal to half Buffer.poolSize. The
+difference is subtle but can be important when an application requires the
+additional performance that Buffer.allocUnsafe() provides.
The desired length of the new Buffer.
Allocates a new Buffer of size bytes. If size is larger than constants.MAX_LENGTH or smaller than 0, ERR_OUT_OF_RANGE is thrown. A zero-length Buffer is created if
+size is 0.
The underlying memory for Buffer instances created in this way is not
+initialized. The contents of the newly created Buffer are unknown and may contain sensitive data. Use buf.fill(0) to initialize
+such Buffer instances with zeroes.
When using Buffer.allocUnsafe() to allocate new Buffer instances,
+allocations under 4 KiB are sliced from a single pre-allocated Buffer. This
+allows applications to avoid the garbage collection overhead of creating many
+individually allocated Buffer instances. This approach improves both
+performance and memory usage by eliminating the need to track and clean up as
+many individual ArrayBuffer objects.
However, in the case where a developer may need to retain a small chunk of
+memory from a pool for an indeterminate amount of time, it may be appropriate
+to create an un-pooled Buffer instance using Buffer.allocUnsafeSlow() and
+then copying out the relevant bits.
import { Buffer } from 'node:buffer';
// Need to keep around a few small chunks of memory.
const store = [];
socket.on('readable', () => {
let data;
while (null !== (data = readable.read())) {
// Allocate for retained data.
const sb = Buffer.allocUnsafeSlow(10);
// Copy the data into the new allocation.
data.copy(sb, 0, 0, 10);
store.push(sb);
}
});
+A TypeError will be thrown if size is not a number.
The desired length of the new Buffer.
Returns the byte length of a string when encoded using encoding.
+This is not the same as String.prototype.length, which does not account
+for the encoding that is used to convert the string into bytes.
For 'base64', 'base64url', and 'hex', this function assumes valid input.
+For strings that contain non-base64/hex-encoded data (e.g. whitespace), the
+return value might be greater than the length of a Buffer created from the
+string.
import { Buffer } from 'node:buffer';
const str = '\u00bd + \u00bc = \u00be';
console.log(`${str}: ${str.length} characters, ` +
`${Buffer.byteLength(str, 'utf8')} bytes`);
// Prints: ½ + ¼ = ¾: 9 characters, 12 bytes
+When string is a
+Buffer/DataView/[TypedArray](https://developer.mozilla.org/en-US/docs/Web/JavaScript/-
+Reference/Global_Objects/TypedArray)/ArrayBuffer/[SharedArrayBuffer](https://develop-
+er.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer), the byte length as reported by .byteLengthis returned.
A value to calculate the length of.
+Optionalencoding: BufferEncodingIf string is a string, this is its encoding.
The number of bytes contained within string.
Compares buf1 to buf2, typically for the purpose of sorting arrays of Buffer instances. This is equivalent to calling buf1.compare(buf2).
import { Buffer } from 'node:buffer';
const buf1 = Buffer.from('1234');
const buf2 = Buffer.from('0123');
const arr = [buf1, buf2];
console.log(arr.sort(Buffer.compare));
// Prints: [ <Buffer 30 31 32 33>, <Buffer 31 32 33 34> ]
// (This result is equal to: [buf2, buf1].)
+Either -1, 0, or 1, depending on the result of the comparison. See compare for details.
Returns a new Buffer which is the result of concatenating all the Buffer instances in the list together.
If the list has no items, or if the totalLength is 0, then a new zero-length Buffer is returned.
If totalLength is not provided, it is calculated from the Buffer instances
+in list by adding their lengths.
If totalLength is provided, it is coerced to an unsigned integer. If the
+combined length of the Buffers in list exceeds totalLength, the result is
+truncated to totalLength.
import { Buffer } from 'node:buffer';
// Create a single `Buffer` from a list of three `Buffer` instances.
const buf1 = Buffer.alloc(10);
const buf2 = Buffer.alloc(14);
const buf3 = Buffer.alloc(18);
const totalLength = buf1.length + buf2.length + buf3.length;
console.log(totalLength);
// Prints: 42
const bufA = Buffer.concat([buf1, buf2, buf3], totalLength);
console.log(bufA);
// Prints: <Buffer 00 00 00 00 ...>
console.log(bufA.length);
// Prints: 42
+Buffer.concat() may also use the internal Buffer pool like Buffer.allocUnsafe() does.
List of Buffer or Uint8Array instances to concatenate.
OptionaltotalLength: numberTotal length of the Buffer instances in list when concatenated.
Copies the underlying memory of view into a new Buffer.
const u16 = new Uint16Array([0, 0xffff]);
const buf = Buffer.copyBytesFrom(u16, 1, 1);
u16[1] = 0;
console.log(buf.length); // 2
console.log(buf[0]); // 255
console.log(buf[1]); // 255
+The {TypedArray} to copy.
+Optionaloffset: numberThe starting offset within view.
Optionallength: numberThe number of elements from view to copy.
Allocates a new Buffer using an array of bytes in the range 0 – 255.
+Array entries outside that range will be truncated to fit into it.
import { Buffer } from 'node:buffer';
// Creates a new Buffer containing the UTF-8 bytes of the string 'buffer'.
const buf = Buffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);
+If array is an Array-like object (that is, one with a length property of
+type number), it is treated as if it is an array, unless it is a Buffer or
+a Uint8Array. This means all other TypedArray variants get treated as an Array. To create a Buffer from the bytes backing a TypedArray, use Buffer.copyBytesFrom().
A TypeError will be thrown if array is not an Array or another type
+appropriate for Buffer.from() variants.
Buffer.from(array) and Buffer.from(string) may also use the internal Buffer pool like Buffer.allocUnsafe() does.
OptionalbyteOffset: numberOptionallength: numberCreates a new Buffer using the passed {data}
+data to create a new Buffer
+Creates a new Buffer containing the given JavaScript string {str}. +If provided, the {encoding} parameter identifies the character encoding. +If not provided, {encoding} defaults to 'utf8'.
+Optionalencoding: BufferEncodingReturns true if obj is a Buffer, false otherwise.
import { Buffer } from 'node:buffer';
Buffer.isBuffer(Buffer.alloc(10)); // true
Buffer.isBuffer(Buffer.from('foo')); // true
Buffer.isBuffer('a string'); // false
Buffer.isBuffer([]); // false
Buffer.isBuffer(new Uint8Array(1024)); // false
+Returns true if encoding is the name of a supported character encoding,
+or false otherwise.
import { Buffer } from 'node:buffer';
console.log(Buffer.isEncoding('utf8'));
// Prints: true
console.log(Buffer.isEncoding('hex'));
// Prints: true
console.log(Buffer.isEncoding('utf/8'));
// Prints: false
console.log(Buffer.isEncoding(''));
// Prints: false
+A character encoding name to check.
+Optional[captureAlias for emitter.on(eventName, listener).
Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments
+to each.
Returns true if the event had listeners, false otherwise.
import { EventEmitter } from 'node:events';
const myEmitter = new EventEmitter();
// First listener
myEmitter.on('event', function firstListener() {
console.log('Helloooo! first listener');
});
// Second listener
myEmitter.on('event', function secondListener(arg1, arg2) {
console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
});
// Third listener
myEmitter.on('event', function thirdListener(...args) {
const parameters = args.join(', ');
console.log(`event with parameters ${parameters} in third listener`);
});
console.log(myEmitter.listeners('event'));
myEmitter.emit('event', 1, 2, 3, 4, 5);
// Prints:
// [
// [Function: firstListener],
// [Function: secondListener],
// [Function: thirdListener]
// ]
// Helloooo! first listener
// event with parameters 1, 2 in second listener
// event with parameters 1, 2, 3, 4, 5 in third listener
+Returns an array listing the events for which the emitter has registered
+listeners. The values in the array are strings or Symbols.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => {});
myEE.on('bar', () => {});
const sym = Symbol('symbol');
myEE.on(sym, () => {});
console.log(myEE.eventNames());
// Prints: [ 'foo', 'bar', Symbol(symbol) ]
+Returns the number of listeners listening for the event named eventName.
+If listener is provided, it will return how many times the listener is found
+in the list of the listeners of the event.
Returns a copy of the array of listeners for the event named eventName.
server.on('connection', (stream) => {
console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')));
// Prints: [ [Function] ]
+Alias for emitter.removeListener().
Adds the listener function to the end of the listeners array for the event
+named eventName. No checks are made to see if the listener has already
+been added. Multiple calls passing the same combination of eventName and
+listener will result in the listener being added, and called, multiple times.
server.on('connection', (stream) => {
console.log('someone connected!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the
+event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
+Adds a one-time listener function for the event named eventName. The
+next time eventName is triggered, this listener is removed and then invoked.
server.once('connection', (stream) => {
console.log('Ah, we have our first user!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the
+event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
+Adds the listener function to the beginning of the listeners array for the
+event named eventName. No checks are made to see if the listener has
+already been added. Multiple calls passing the same combination of eventName
+and listener will result in the listener being added, and called, multiple times.
server.prependListener('connection', (stream) => {
console.log('someone connected!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
Adds a one-timelistener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this
+listener is removed, and then invoked.
server.prependOnceListener('connection', (stream) => {
console.log('Ah, we have our first user!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
Returns a copy of the array of listeners for the event named eventName,
+including any wrappers (such as those created by .once()).
import { EventEmitter } from 'node:events';
const emitter = new EventEmitter();
emitter.once('log', () => console.log('log once'));
// Returns a new Array with a function `onceWrapper` which has a property
// `listener` which contains the original listener bound above
const listeners = emitter.rawListeners('log');
const logFnWrapper = listeners[0];
// Logs "log once" to the console and does not unbind the `once` event
logFnWrapper.listener();
// Logs "log once" to the console and removes the listener
logFnWrapper();
emitter.on('log', () => console.log('log persistently'));
// Will return a new Array with a single function bound by `.on()` above
const newListeners = emitter.rawListeners('log');
// Logs "log persistently" twice
newListeners[0]();
emitter.emit('log');
+Removes all listeners, or those of the specified eventName.
It is bad practice to remove listeners added elsewhere in the code,
+particularly when the EventEmitter instance was created by some other
+component or module (e.g. sockets or file streams).
Returns a reference to the EventEmitter, so that calls can be chained.
Removes the specified listener from the listener array for the event named eventName.
const callback = (stream) => {
console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);
+removeListener() will remove, at most, one instance of a listener from the
+listener array. If any single listener has been added multiple times to the
+listener array for the specified eventName, then removeListener() must be
+called multiple times to remove each instance.
Once an event is emitted, all listeners attached to it at the
+time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution
+will not remove them fromemit() in progress. Subsequent events behave as expected.
import { EventEmitter } from 'node:events';
class MyEmitter extends EventEmitter {}
const myEmitter = new MyEmitter();
const callbackA = () => {
console.log('A');
myEmitter.removeListener('event', callbackB);
};
const callbackB = () => {
console.log('B');
};
myEmitter.on('event', callbackA);
myEmitter.on('event', callbackB);
// callbackA removes listener callbackB but it will still be called.
// Internal listener array at time of emit [callbackA, callbackB]
myEmitter.emit('event');
// Prints:
// A
// B
// callbackB is now removed.
// Internal listener array [callbackA]
myEmitter.emit('event');
// Prints:
// A
+Because listeners are managed using an internal array, calling this will
+change the position indices of any listener registered after the listener
+being removed. This will not impact the order in which listeners are called,
+but it means that any copies of the listener array as returned by
+the emitter.listeners() method will need to be recreated.
When a single function has been added as a handler multiple times for a single
+event (as in the example below), removeListener() will remove the most
+recently added instance. In the example the once('ping') listener is removed:
import { EventEmitter } from 'node:events';
const ee = new EventEmitter();
function pong() {
console.log('pong');
}
ee.on('ping', pong);
ee.once('ping', pong);
ee.removeListener('ping', pong);
ee.emit('ping');
ee.emit('ping');
+Returns a reference to the EventEmitter, so that calls can be chained.
By default EventEmitters will print a warning if more than 10 listeners are
+added for a particular event. This is a useful default that helps finding
+memory leaks. The emitter.setMaxListeners() method allows the limit to be
+modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.
Returns a reference to the EventEmitter, so that calls can be chained.
Rest...args: [] | [TNext]Rest...args: [] | [undefined]OptionalreturnOptionalvalue: anyOptionalthrowOptionale: anyRest...args: [] | [TNext]OptionalreturnOptionalvalue: TReturnOptionalthrowOptionale: anyOptionalcacheWhether or not to cache resolved templates. Defaults to false.
OptionalcatchCatch all errors instead of exit upon one. Please note that render errors won't be reached when parse fails.
+Default date format to use if the date filter doesn't include a format. Defaults to %A, %B %-e, %Y at %-l:%M %P %z.
If set, treat the filepath parameter in {%include filepath %} and {%layout filepath%} as a variable, otherwise as a literal value. Defaults to true.
Add a extname (if filepath doesn't include one) before template file lookup. Eg: setting to ".html" will allow including file by basename. Defaults to "".
fs is used to override the default file-system module with a custom implementation.
the global scope passed down to all partial and layout templates, i.e. templates included by include, layout and render tags.
Whether trim*Left/trim*Right is greedy. When set to true, all consecutive blank characters including \n will be trimmed regardless of line breaks. Defaults to true.
Use jekyll style include, pass parameters to include variable of current scope. Defaults to false.
OptionaljekyllUse jekyll style where filter, enables array item match. Defaults to false.
Use JavaScript Truthiness. Defaults to false.
Whether or not to keep value type when writing the Output, not working for streamed rendering. Defaults to false.
OptionalkeykeyValue separator
+A directory or an array of directories from where to resolve layout templates. If it's an array, the files are looked up in the order they occur in the array. Defaults to root
Modifies the behavior of strictVariables. If set, a single undefined variable will not cause an exception in the context of the if/elsif/unless tag and the default filter. Instead, it will evaluate to false and null, respectively. Irrelevant if strictVariables is not set. Defaults to false. *
Default locale, will be used by date filter. Defaults to system locale.
+For DoS handling, limit new objects creation, including array concat/join/strftime, etc. A typical PC can handle 1e9 (1G) memory without issue.
+An object of operators for conditional statements. Defaults to the regular Liquid operators.
+OptionalorderedRespect parameter order when using filters like "for ... reversed limit", Defaults to false.
The left delimiter for liquid outputs. *
+The right delimiter for liquid outputs. *
+OptionaloutputDefault escape filter applied to output values, when set, you'll have to add | raw for values don't need to be escaped. Defaults to undefined.
Hide scope variables from prototypes, useful when you're passing a not sanitized object into LiquidJS or need to hide prototypes from templates.
+For DoS handling, limit total length of templates parsed in one parse() call. A typical PC can handle 1e8 (100M) characters without issues.
A directory or an array of directories from where to resolve included templates. If it's an array, the files are looked up in the order they occur in the array. Defaults to root
Whether input strings to date filter preserve the given timezone *
+Allow refer to layouts/partials by relative pathname. To avoid arbitrary filesystem read, paths been referenced also need to be within corresponding root, partials, layouts. Defaults to true.
For DoS handling, limit total time (in ms) for each render() call.
A directory or an array of directories from where to resolve layout and include templates, and the filename passed to .renderFile(). If it's an array, the files are looked up in the order they occur in the array. Defaults to ["."]
Whether or not to assert filter existence. If set to false, undefined filters will be skipped. Otherwise, undefined filters will cause an exception. Defaults to false.
Whether or not to assert variable existence. If set to false, undefined variables will be rendered as empty string. Otherwise, undefined variables will cause an exception. Defaults to false.
The left delimiter for liquid tags. *
+The right delimiter for liquid tags. *
+OptionaltemplatesRender from in-memory templates mapping instead of file system. File system related options like fs, 'root', and relativeReference will be ignored when templates is specified.
OptionaltimezoneJavaScript timezone name or timezoneOffset for date filter, default to local time. That means if you're in Australia (UTC+10), it'll default to -600 or Australia/Lindeman
Similar to trimOutputRight, whereas the \n is exclusive. Defaults to false. See Whitespace Control for details.
Strip blank characters (including , \t, and \r) from the right of values ({{ }}) until \n (inclusive). Defaults to false.
Similar to trimTagRight, whereas the \n is exclusive. Defaults to false. See Whitespace Control for details.
Strip blank characters (including , \t, and \r) from the right of tags ({% %}) until \n (inclusive). Defaults to false.
OptionalcacheWhether or not to cache resolved templates. Defaults to false.
OptionalcatchCatch all errors instead of exit upon one. Please note that render errors won't be reached when parse fails.
+OptionaldateDefault date format to use if the date filter doesn't include a format. Defaults to %A, %B %-e, %Y at %-l:%M %P %z.
OptionaldynamicIf set, treat the filepath parameter in {%include filepath %} and {%layout filepath%} as a variable, otherwise as a literal value. Defaults to true.
OptionalextnameAdd a extname (if filepath doesn't include one) before template file lookup. Eg: setting to ".html" will allow including file by basename. Defaults to "".
Optionalfsfs is used to override the default file-system module with a custom implementation.
Optionalglobalsthe global scope passed down to all partial and layout templates, i.e. templates included by include, layout and render tags.
OptionalgreedyWhether trim*Left/trim*Right is greedy. When set to true, all consecutive blank characters including \n will be trimmed regardless of line breaks. Defaults to true.
OptionaljekyllUse jekyll style include, pass parameters to include variable of current scope. Defaults to false.
OptionaljekyllUse jekyll style where filter, enables array item match. Defaults to false.
OptionaljsUse JavaScript Truthiness. Defaults to false.
OptionalkeepWhether or not to keep value type when writing the Output, not working for streamed rendering. Defaults to false.
OptionalkeykeyValue separator
+OptionallayoutsA directory or an array of directories from where to resolve layout templates. If it's an array, the files are looked up in the order they occur in the array. Defaults to root
OptionallenientModifies the behavior of strictVariables. If set, a single undefined variable will not cause an exception in the context of the if/elsif/unless tag and the default filter. Instead, it will evaluate to false and null, respectively. Irrelevant if strictVariables is not set. Defaults to false. *
OptionallocaleDefault locale, will be used by date filter. Defaults to system locale.
+OptionalmemoryFor DoS handling, limit new objects creation, including array concat/join/strftime, etc. A typical PC can handle 1e9 (1G) memory without issue.
+OptionaloperatorsAn object of operators for conditional statements. Defaults to the regular Liquid operators.
+OptionalorderedRespect parameter order when using filters like "for ... reversed limit", Defaults to false.
OptionaloutputThe left delimiter for liquid outputs. *
+OptionaloutputThe right delimiter for liquid outputs. *
+OptionaloutputDefault escape filter applied to output values, when set, you'll have to add | raw for values don't need to be escaped. Defaults to undefined.
OptionalownHide scope variables from prototypes, useful when you're passing a not sanitized object into LiquidJS or need to hide prototypes from templates.
+OptionalparseFor DoS handling, limit total length of templates parsed in one parse() call. A typical PC can handle 1e8 (100M) characters without issues.
OptionalpartialsA directory or an array of directories from where to resolve included templates. If it's an array, the files are looked up in the order they occur in the array. Defaults to root
OptionalpreserveWhether input strings to date filter preserve the given timezone *
+OptionalrelativeAllow refer to layouts/partials by relative pathname. To avoid arbitrary filesystem read, paths been referenced also need to be within corresponding root, partials, layouts. Defaults to true.
OptionalrenderFor DoS handling, limit total time (in ms) for each render() call.
OptionalrootA directory or an array of directories from where to resolve layout and include templates, and the filename passed to .renderFile(). If it's an array, the files are looked up in the order they occur in the array. Defaults to ["."]
OptionalstrictWhether or not to assert filter existence. If set to false, undefined filters will be skipped. Otherwise, undefined filters will cause an exception. Defaults to false.
OptionalstrictWhether or not to assert variable existence. If set to false, undefined variables will be rendered as empty string. Otherwise, undefined variables will cause an exception. Defaults to false.
OptionaltagThe left delimiter for liquid tags. *
+OptionaltagThe right delimiter for liquid tags. *
+OptionaltemplatesRender from in-memory templates mapping instead of file system. File system related options like fs, 'root', and relativeReference will be ignored when templates is specified.
OptionaltimezoneJavaScript timezone name or timezoneOffset for date filter, default to local time. That means if you're in Australia (UTC+10), it'll default to -600 or Australia/Lindeman
OptionaltrimSimilar to trimOutputRight, whereas the \n is exclusive. Defaults to false. See Whitespace Control for details.
OptionaltrimStrip blank characters (including , \t, and \r) from the right of values ({{ }}) until \n (inclusive). Defaults to false.
OptionaltrimSimilar to trimTagRight, whereas the \n is exclusive. Defaults to false. See Whitespace Control for details.
OptionaltrimStrip blank characters (including , \t, and \r) from the right of tags ({% %}) until \n (inclusive). Defaults to false.
Attaches callbacks for the resolution and/or rejection of the Promise.
+Optionalonfulfilled: null | ((value: T) => TResult1 | PromiseLike<TResult1>)The callback to execute when the Promise is resolved.
+Optionalonrejected: null | ((reason: any) => TResult2 | PromiseLike<TResult2>)The callback to execute when the Promise is rejected.
+A Promise for the completion of which ever callback is executed.
+Optional[captureAlias for emitter.on(eventName, listener).
Rest...args: any[]Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments
+to each.
Returns true if the event had listeners, false otherwise.
import { EventEmitter } from 'node:events';
const myEmitter = new EventEmitter();
// First listener
myEmitter.on('event', function firstListener() {
console.log('Helloooo! first listener');
});
// Second listener
myEmitter.on('event', function secondListener(arg1, arg2) {
console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
});
// Third listener
myEmitter.on('event', function thirdListener(...args) {
const parameters = args.join(', ');
console.log(`event with parameters ${parameters} in third listener`);
});
console.log(myEmitter.listeners('event'));
myEmitter.emit('event', 1, 2, 3, 4, 5);
// Prints:
// [
// [Function: firstListener],
// [Function: secondListener],
// [Function: thirdListener]
// ]
// Helloooo! first listener
// event with parameters 1, 2 in second listener
// event with parameters 1, 2, 3, 4, 5 in third listener
+Rest...args: AnyRestReturns an array listing the events for which the emitter has registered
+listeners. The values in the array are strings or Symbols.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => {});
myEE.on('bar', () => {});
const sym = Symbol('symbol');
myEE.on(sym, () => {});
console.log(myEE.eventNames());
// Prints: [ 'foo', 'bar', Symbol(symbol) ]
+Returns the number of listeners listening for the event named eventName.
+If listener is provided, it will return how many times the listener is found
+in the list of the listeners of the event.
The name of the event being listened for
+Optionallistener: FunctionThe event handler function
+Returns a copy of the array of listeners for the event named eventName.
server.on('connection', (stream) => {
console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')));
// Prints: [ [Function] ]
+Alias for emitter.removeListener().
Rest...args: any[]Adds the listener function to the end of the listeners array for the event
+named eventName. No checks are made to see if the listener has already
+been added. Multiple calls passing the same combination of eventName and
+listener will result in the listener being added, and called, multiple times.
server.on('connection', (stream) => {
console.log('someone connected!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the
+event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
+The name of the event.
+The callback function
+Rest...args: any[]Adds a one-time listener function for the event named eventName. The
+next time eventName is triggered, this listener is removed and then invoked.
server.once('connection', (stream) => {
console.log('Ah, we have our first user!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the
+event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
+The name of the event.
+The callback function
+Rest...args: any[]Adds the listener function to the beginning of the listeners array for the
+event named eventName. No checks are made to see if the listener has
+already been added. Multiple calls passing the same combination of eventName
+and listener will result in the listener being added, and called, multiple times.
server.prependListener('connection', (stream) => {
console.log('someone connected!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
The name of the event.
+The callback function
+Rest...args: any[]Adds a one-timelistener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this
+listener is removed, and then invoked.
server.prependOnceListener('connection', (stream) => {
console.log('Ah, we have our first user!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
The name of the event.
+The callback function
+Rest...args: any[]Returns a copy of the array of listeners for the event named eventName,
+including any wrappers (such as those created by .once()).
import { EventEmitter } from 'node:events';
const emitter = new EventEmitter();
emitter.once('log', () => console.log('log once'));
// Returns a new Array with a function `onceWrapper` which has a property
// `listener` which contains the original listener bound above
const listeners = emitter.rawListeners('log');
const logFnWrapper = listeners[0];
// Logs "log once" to the console and does not unbind the `once` event
logFnWrapper.listener();
// Logs "log once" to the console and removes the listener
logFnWrapper();
emitter.on('log', () => console.log('log persistently'));
// Will return a new Array with a single function bound by `.on()` above
const newListeners = emitter.rawListeners('log');
// Logs "log persistently" twice
newListeners[0]();
emitter.emit('log');
+Removes all listeners, or those of the specified eventName.
It is bad practice to remove listeners added elsewhere in the code,
+particularly when the EventEmitter instance was created by some other
+component or module (e.g. sockets or file streams).
Returns a reference to the EventEmitter, so that calls can be chained.
OptionaleventName: string | symbolRemoves the specified listener from the listener array for the event named eventName.
const callback = (stream) => {
console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);
+removeListener() will remove, at most, one instance of a listener from the
+listener array. If any single listener has been added multiple times to the
+listener array for the specified eventName, then removeListener() must be
+called multiple times to remove each instance.
Once an event is emitted, all listeners attached to it at the
+time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution
+will not remove them fromemit() in progress. Subsequent events behave as expected.
import { EventEmitter } from 'node:events';
class MyEmitter extends EventEmitter {}
const myEmitter = new MyEmitter();
const callbackA = () => {
console.log('A');
myEmitter.removeListener('event', callbackB);
};
const callbackB = () => {
console.log('B');
};
myEmitter.on('event', callbackA);
myEmitter.on('event', callbackB);
// callbackA removes listener callbackB but it will still be called.
// Internal listener array at time of emit [callbackA, callbackB]
myEmitter.emit('event');
// Prints:
// A
// B
// callbackB is now removed.
// Internal listener array [callbackA]
myEmitter.emit('event');
// Prints:
// A
+Because listeners are managed using an internal array, calling this will
+change the position indices of any listener registered after the listener
+being removed. This will not impact the order in which listeners are called,
+but it means that any copies of the listener array as returned by
+the emitter.listeners() method will need to be recreated.
When a single function has been added as a handler multiple times for a single
+event (as in the example below), removeListener() will remove the most
+recently added instance. In the example the once('ping') listener is removed:
import { EventEmitter } from 'node:events';
const ee = new EventEmitter();
function pong() {
console.log('pong');
}
ee.on('ping', pong);
ee.once('ping', pong);
ee.removeListener('ping', pong);
ee.emit('ping');
ee.emit('ping');
+Returns a reference to the EventEmitter, so that calls can be chained.
Rest...args: any[]By default EventEmitters will print a warning if more than 10 listeners are
+added for a particular event. This is a useful default that helps finding
+memory leaks. The emitter.setMaxListeners() method allows the limit to be
+modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.
Returns a reference to the EventEmitter, so that calls can be chained.
Optionaldestination: WritableStreamOptionalencoding: BufferEncodingOptionalglobalsSame as globals on LiquidOptions, but only for current render() call
OptionallookupOptionalmemoryFor DoS handling, limit new objects creation, including array concat/join/strftime, etc. A typical PC can handle 1e9 (1G) memory without issue..
+OptionalownSame as ownPropertyOnly on LiquidOptions, but only for current render() call
OptionalrenderFor DoS handling, limit total time (in ms) for each render() call.
OptionalstrictSame as strictVariables on LiquidOptions, but only for current render() call
OptionalsyncThis call is sync or async? It's used by Liquid internal methods, you'll not need this.
+OptionaltemplateFor DoS handling, limit total renders of tag/HTML/output in one render() call. A typical PC can handle 1e5 renders of typical templates per second.
OptionalglobalsSame as globals on LiquidOptions, but only for current render() call
OptionalmemoryFor DoS handling, limit new objects creation, including array concat/join/strftime, etc. A typical PC can handle 1e9 (1G) memory without issue..
+OptionalownSame as ownPropertyOnly on LiquidOptions, but only for current render() call
OptionalrenderFor DoS handling, limit total time (in ms) for each render() call.
OptionalstrictSame as strictVariables on LiquidOptions, but only for current render() call
OptionalsyncThis call is sync or async? It's used by Liquid internal methods, you'll not need this.
+OptionaltemplateFor DoS handling, limit total renders of tag/HTML/output in one render() call. A typical PC can handle 1e5 renders of typical templates per second.
Readonly[species]Readonly[toReadonlybyteRead-only. The length of the ArrayBuffer (in bytes).
+Returns a section of an SharedArrayBuffer.
+Optionalend: numberOptionalparseOptional[captureAlias for emitter.on(eventName, listener).
Rest...args: any[]Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments
+to each.
Returns true if the event had listeners, false otherwise.
import { EventEmitter } from 'node:events';
const myEmitter = new EventEmitter();
// First listener
myEmitter.on('event', function firstListener() {
console.log('Helloooo! first listener');
});
// Second listener
myEmitter.on('event', function secondListener(arg1, arg2) {
console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
});
// Third listener
myEmitter.on('event', function thirdListener(...args) {
const parameters = args.join(', ');
console.log(`event with parameters ${parameters} in third listener`);
});
console.log(myEmitter.listeners('event'));
myEmitter.emit('event', 1, 2, 3, 4, 5);
// Prints:
// [
// [Function: firstListener],
// [Function: secondListener],
// [Function: thirdListener]
// ]
// Helloooo! first listener
// event with parameters 1, 2 in second listener
// event with parameters 1, 2, 3, 4, 5 in third listener
+Rest...args: AnyRestOptionalcb: (() => void)Optionalcb: (() => void)Optionalencoding: BufferEncodingOptionalcb: (() => void)Returns an array listing the events for which the emitter has registered
+listeners. The values in the array are strings or Symbols.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => {});
myEE.on('bar', () => {});
const sym = Symbol('symbol');
myEE.on(sym, () => {});
console.log(myEE.eventNames());
// Prints: [ 'foo', 'bar', Symbol(symbol) ]
+Returns the number of listeners listening for the event named eventName.
+If listener is provided, it will return how many times the listener is found
+in the list of the listeners of the event.
The name of the event being listened for
+Optionallistener: FunctionThe event handler function
+Returns a copy of the array of listeners for the event named eventName.
server.on('connection', (stream) => {
console.log('someone connected!');
});
console.log(util.inspect(server.listeners('connection')));
// Prints: [ [Function] ]
+Alias for emitter.removeListener().
Rest...args: any[]Adds the listener function to the end of the listeners array for the event
+named eventName. No checks are made to see if the listener has already
+been added. Multiple calls passing the same combination of eventName and
+listener will result in the listener being added, and called, multiple times.
server.on('connection', (stream) => {
console.log('someone connected!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the
+event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
+The name of the event.
+The callback function
+Rest...args: any[]Adds a one-time listener function for the event named eventName. The
+next time eventName is triggered, this listener is removed and then invoked.
server.once('connection', (stream) => {
console.log('Ah, we have our first user!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the
+event listener to the beginning of the listeners array.
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
+The name of the event.
+The callback function
+Rest...args: any[]Adds the listener function to the beginning of the listeners array for the
+event named eventName. No checks are made to see if the listener has
+already been added. Multiple calls passing the same combination of eventName
+and listener will result in the listener being added, and called, multiple times.
server.prependListener('connection', (stream) => {
console.log('someone connected!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
The name of the event.
+The callback function
+Rest...args: any[]Adds a one-timelistener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this
+listener is removed, and then invoked.
server.prependOnceListener('connection', (stream) => {
console.log('Ah, we have our first user!');
});
+Returns a reference to the EventEmitter, so that calls can be chained.
The name of the event.
+The callback function
+Rest...args: any[]Returns a copy of the array of listeners for the event named eventName,
+including any wrappers (such as those created by .once()).
import { EventEmitter } from 'node:events';
const emitter = new EventEmitter();
emitter.once('log', () => console.log('log once'));
// Returns a new Array with a function `onceWrapper` which has a property
// `listener` which contains the original listener bound above
const listeners = emitter.rawListeners('log');
const logFnWrapper = listeners[0];
// Logs "log once" to the console and does not unbind the `once` event
logFnWrapper.listener();
// Logs "log once" to the console and removes the listener
logFnWrapper();
emitter.on('log', () => console.log('log persistently'));
// Will return a new Array with a single function bound by `.on()` above
const newListeners = emitter.rawListeners('log');
// Logs "log persistently" twice
newListeners[0]();
emitter.emit('log');
+Removes all listeners, or those of the specified eventName.
It is bad practice to remove listeners added elsewhere in the code,
+particularly when the EventEmitter instance was created by some other
+component or module (e.g. sockets or file streams).
Returns a reference to the EventEmitter, so that calls can be chained.
OptionaleventName: string | symbolRemoves the specified listener from the listener array for the event named eventName.
const callback = (stream) => {
console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);
+removeListener() will remove, at most, one instance of a listener from the
+listener array. If any single listener has been added multiple times to the
+listener array for the specified eventName, then removeListener() must be
+called multiple times to remove each instance.
Once an event is emitted, all listeners attached to it at the
+time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution
+will not remove them fromemit() in progress. Subsequent events behave as expected.
import { EventEmitter } from 'node:events';
class MyEmitter extends EventEmitter {}
const myEmitter = new MyEmitter();
const callbackA = () => {
console.log('A');
myEmitter.removeListener('event', callbackB);
};
const callbackB = () => {
console.log('B');
};
myEmitter.on('event', callbackA);
myEmitter.on('event', callbackB);
// callbackA removes listener callbackB but it will still be called.
// Internal listener array at time of emit [callbackA, callbackB]
myEmitter.emit('event');
// Prints:
// A
// B
// callbackB is now removed.
// Internal listener array [callbackA]
myEmitter.emit('event');
// Prints:
// A
+Because listeners are managed using an internal array, calling this will
+change the position indices of any listener registered after the listener
+being removed. This will not impact the order in which listeners are called,
+but it means that any copies of the listener array as returned by
+the emitter.listeners() method will need to be recreated.
When a single function has been added as a handler multiple times for a single
+event (as in the example below), removeListener() will remove the most
+recently added instance. In the example the once('ping') listener is removed:
import { EventEmitter } from 'node:events';
const ee = new EventEmitter();
function pong() {
console.log('pong');
}
ee.on('ping', pong);
ee.once('ping', pong);
ee.removeListener('ping', pong);
ee.emit('ping');
ee.emit('ping');
+Returns a reference to the EventEmitter, so that calls can be chained.
Rest...args: any[]By default EventEmitters will print a warning if more than 10 listeners are
+added for a particular event. This is a useful default that helps finding
+memory leaks. The emitter.setMaxListeners() method allows the limit to be
+modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.
Returns a reference to the EventEmitter, so that calls can be chained.
Optionalencoding: BufferEncodingOptionalcb: ((err?: null | Error) => void)Optionalerr: null | ErrorProperty names and array indexes that make up a path to a variable.
+A mapping of variable names to an array of locations at which the variable was found.
+A variable's segments as an array, possibly with nested arrays of segments.
+ConstConstConstConst
Optional override for formatting stack traces
+