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Build Docs Reference Guides Blog Discord/node:buffer Fatob Fbtoa Vconstants VINSPECT_MAX_BYTES FisAscii FisUtf8 VkMaxLength VkStringMaxLength FresolveObjectURL Ftranscode

Node.js module

bufferThe 'node:buffer' module provides a way to handle raw binary data directly in memory. Buffers are instances of the Buffer class, which is a fixed-length sequence of bytes.

The module includes methods to create, read, write, concatenate, and compare buffers. It is fundamental for I/O operations, such as reading files, handling network streams, and interfacing with C++ addons.

Works in Bun

Fully implemented.

const Blob: new (blobParts?: BlobPart[], options?: BlobPropertyBag) => Blobconst Buffer: BufferConstructorconst constants: { MAX_LENGTH: number; MAX_STRING_LENGTH: number }const File: new (fileBits: BlobPart[], fileName: string, options?: FilePropertyBag) => Fileconst INSPECT_MAX_BYTES: numberconst kMaxLength: numberconst kStringMaxLength: numberfunction atob(data: string): string;MDN Reference

function btoa(data: string): string;MDN Reference

function isAscii(input: ArrayBuffer | TypedArrayArrayBufferLike>): boolean;This function returns true if input contains only valid ASCII-encoded data, including the case in which input is empty.

Throws if the input is a detached array buffer.

@param inputThe input to validate.

function isUtf8(input: ArrayBuffer | TypedArrayArrayBufferLike>): boolean;This function returns true if input contains only valid UTF-8-encoded data, including the case in which input is empty.

Throws if the input is a detached array buffer.

@param inputThe input to validate.

function resolveObjectURL(id: string): undefined | Blob;Resolves a 'blob:nodedata:...' an associated Blob object registered using a prior call to URL.createObjectURL().

@param idA 'blob:nodedata:... URL string returned by a prior call to URL.createObjectURL().

function transcode(source: Uint8Array,fromEnc: TranscodeEncoding,toEnc: TranscodeEncoding): NonSharedBuffer;Re-encodes the given Buffer or Uint8Array instance from one character encoding to another. Returns a new Buffer instance.

Throws if the fromEnc or toEnc specify invalid character encodings or if conversion from fromEnc to toEnc is not permitted.

Encodings supported by buffer.transcode() are: 'ascii', 'utf8', 'utf16le', 'ucs2', 'latin1', and 'binary'.

The transcoding process will use substitution characters if a given byte sequence cannot be adequately represented in the target encoding. For instance:

import { Buffer, transcode } from 'node:buffer'; const newBuf = transcode(Buffer.from('€'), 'utf8', 'ascii'); console.log(newBuf.toString('ascii')); // Prints: '?' Because the Euro (€) sign is not representable in US-ASCII, it is replaced with ? in the transcoded Buffer.

@param sourceA Buffer or Uint8Array instance.

@param fromEncThe current encoding.

@param toEncTo target encoding.

Type definitionsinterface Blobreadonly size: numberreadonly type: stringarrayBuffer(): PromiseArrayBuffer>;Consume the blob as an ArrayBuffer

bytes(): PromiseNonSharedUint8Array>;bytes(): PromiseUint8Array ArrayBuffer>>;Consume as a Uint8Array, backed by an ArrayBuffer

slice(start?: number,end?: number,contentType?: string): Blob;stream(): ReadableStreamNonSharedUint8Array>;stream(): ReadableStream Uint8Array ArrayBuffer>>;Returns a readable stream of the blob's contents

text(): Promisestring>;interface BlobPropertyBag endings?: 'native' | 'transparent'type?: stringinterface BufferTArrayBuffer extends ArrayBufferLike = ArrayBufferLike>A typed array of 8-bit unsigned integer values. The contents are initialized to 0. If the requested number of bytes could not be allocated an exception is raised.

readonly [Symbol.toStringTag]: 'Uint8Array'readonly buffer: TArrayBufferThe ArrayBuffer instance referenced by the array.

readonly byteLength: numberThe length in bytes of the array.

readonly byteOffset: numberThe offset in bytes of the array.

readonly BYTES_PER_ELEMENT: numberThe size in bytes of each element in the array.

readonly length: numberThe length of the array.

[Symbol.iterator](): ArrayIteratornumber>;at(index: number): undefined | number;Returns the item located at the specified index.

@param indexThe zero-based index of the desired code unit. A negative index will count back from the last item.

, , ] // (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. ```js 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 target.byteLength`, or `sourceEnd > source.byteLength`." data-algolia-static="false" data-algolia-merged="false" data-type="Method">compare(target: Uint8Array,targetStart?: number,targetEnd?: number,sourceStart?: number,sourceEnd?: number): -1 | 0 | 1;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: [ , , ] // (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 , sourceStart , targetEnd > target.byteLength, or sourceEnd > source.byteLength.

@param targetA Buffer or Uint8Array with which to compare buf.

@param targetStartThe offset within target at which to begin comparison.

@param targetEndThe offset within target at which to end comparison (not inclusive).

@param sourceStartThe offset within buf at which to begin comparison.

@param sourceEndThe offset within buf at which to end comparison (not inclusive).

copy(target: Uint8Array,targetStart?: number,sourceStart?: number,sourceEnd?: number): number;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 @param targetA Buffer or Uint8Array to copy into.

@param targetStartThe offset within target at which to begin writing.

@param sourceStartThe offset within buf from which to begin copying.

@param sourceEndThe offset within buf at which to stop copying (not inclusive).

@returnsThe number of bytes copied.

copyWithin(target: number,start: number,end?: number): this;Returns the this object after copying a section of the array identified by start and end to the same array starting at position target

@param targetIf target is negative, it is treated as length+target where length is the length of the array.

@param startIf start is negative, it is treated as length+start. If end is negative, it is treated as length+end.

@param endIf not specified, length of the this object is used as its default value.

entries(): ArrayIterator[number, number]>;Returns an array of key, value pairs for every entry in the array

equals(otherBuffer: Uint8Array): boolean;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 @param otherBufferA Buffer or Uint8Array with which to compare buf.

every(predicate: (value: number, index: number, array: this) => unknown,thisArg?: any): boolean;Determines whether all the members of an array satisfy the specified test.

@param predicateA 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.

@param thisArgAn object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.

``` `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: ```js 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: ``` If `value` contains invalid characters, it is truncated; if no valid fill data remains, an exception is thrown: ```js import { Buffer } from 'node:buffer'; const buf = Buffer.allocUnsafe(5); console.log(buf.fill('a')); // Prints: console.log(buf.fill('aazz', 'hex')); // Prints: console.log(buf.fill('zz', 'hex')); // Throws an exception. ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">fill(value: string | number | Uint8ArrayArrayBufferLike>,offset?: number,end?: number,encoding?: BufferEncoding): this;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: 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: 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: console.log(buf.fill('aazz', 'hex')); // Prints: console.log(buf.fill('zz', 'hex')); // Throws an exception. @param valueThe value with which to fill buf. Empty value (string, Uint8Array, Buffer) is coerced to 0.

@param offsetNumber of bytes to skip before starting to fill buf.

@param endWhere to stop filling buf (not inclusive).

@param encodingThe encoding for value if value is a string.

@returnsA reference to buf.

fill(value: string | number | Uint8ArrayArrayBufferLike>,offset: number,encoding: BufferEncoding): this;fill(value: string | number | Uint8ArrayArrayBufferLike>,encoding: BufferEncoding): this;filter(predicate: (value: number, index: number, array: this) => any,thisArg?: any): Uint8Array ArrayBuffer>;Returns the elements of an array that meet the condition specified in a callback function.

@param predicateA function that accepts up to three arguments. The filter method calls the predicate function one time for each element in the array.

@param thisArgAn object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.

find(predicate: (value: number, index: number, obj: this) => boolean,thisArg?: any): undefined | number;Returns the value of the first element in the array where predicate is true, and undefined otherwise.

@param predicatefind 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.

@param thisArgIf provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.

findIndex(predicate: (value: number, index: number, obj: this) => boolean,thisArg?: any): number;Returns the index of the first element in the array where predicate is true, and -1 otherwise.

@param predicatefind 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.

@param thisArgIf provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.

findLastS extends number>(predicate: (value: number, index: number, array: this) => value is S,thisArg?: any): undefined | S;Returns the value of the last element in the array where predicate is true, and undefined otherwise.

@param predicatefindLast calls predicate once for each element of the array, in descending order, until it finds one where predicate returns true. If such an element is found, findLast immediately returns that element value. Otherwise, findLast returns undefined.

@param thisArgIf provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.

findLast(predicate: (value: number, index: number, array: this) => unknown,thisArg?: any): undefined | number;findLastIndex(predicate: (value: number, index: number, array: this) => unknown,thisArg?: any): number;Returns the index of the last element in the array where predicate is true, and -1 otherwise.

@param predicatefindLastIndex calls predicate once for each element of the array, in descending order, until it finds one where predicate returns true. If such an element is found, findLastIndex immediately returns that element index. Otherwise, findLastIndex returns -1.

@param thisArgIf provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.

forEach(callbackfn: (value: number, index: number, array: this) => void,thisArg?: any): void;Performs the specified action for each element in an array.

@param callbackfnA function that accepts up to three arguments. forEach calls the callbackfn function one time for each element in the array.

@param thisArgAn object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

includes(value: string | number | BufferArrayBufferLike>,byteOffset?: number,encoding?: BufferEncoding): boolean;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 @param valueWhat to search for.

@param byteOffsetWhere to begin searching in buf. If negative, then offset is calculated from the end of buf.

@param encodingIf value is a string, this is its encoding.

@returnstrue if value was found in buf, false otherwise.

includes(value: string | number | BufferArrayBufferLike>,encoding: BufferEncoding): boolean;indexOf(value: string | number | Uint8ArrayArrayBufferLike>,byteOffset?: number,encoding?: BufferEncoding): number;If value is:

a string, value is interpreted according to the character encoding in encoding.a Buffer or Uint8Array, value will be used in its entirety. To compare a partial Buffer, use buf.subarray.a number, 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.

@param valueWhat to search for.

@param byteOffsetWhere to begin searching in buf. If negative, then offset is calculated from the end of buf.

@param encodingIf value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf.

@returnsThe index of the first occurrence of value in buf, or -1 if buf does not contain value.

indexOf(value: string | number | Uint8ArrayArrayBufferLike>,encoding: BufferEncoding): number;join(separator?: string): string;Adds all the elements of an array separated by the specified separator string.

@param separatorA 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.

keys(): ArrayIteratornumber>;Returns an list of keys in the array

lastIndexOf(value: string | number | Uint8ArrayArrayBufferLike>,byteOffset?: number,encoding?: BufferEncoding): number;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.

@param valueWhat to search for.

@param byteOffsetWhere to begin searching in buf. If negative, then offset is calculated from the end of buf.

@param encodingIf value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf.

@returnsThe index of the last occurrence of value in buf, or -1 if buf does not contain value.

lastIndexOf(value: string | number | Uint8ArrayArrayBufferLike>,encoding: BufferEncoding): number;map(callbackfn: (value: number, index: number, array: this) => number,thisArg?: any): Uint8Array ArrayBuffer>;Calls a defined callback function on each element of an array, and returns an array that contains the results.

@param callbackfnA function that accepts up to three arguments. The map method calls the callbackfn function one time for each element in the array.

@param thisArgAn object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.

readBigInt64BE(offset?: number): bigint;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.

@param offsetNumber of bytes to skip before starting to read. Must satisfy: 0 .

readBigInt64LE(offset?: number): bigint;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.

@param offsetNumber of bytes to skip before starting to read. Must satisfy: 0 .

readBigUint64BE(offset?: number): bigint;readBigUInt64BE(offset?: number): bigint;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy: 0 .

readBigUint64LE(offset?: number): bigint;readBigUInt64LE(offset?: number): bigint;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy: 0 .

readDoubleBE(offset?: number): number;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readDoubleLE(offset?: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readFloatBE(offset?: number): number;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readFloatLE(offset?: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readInt16BE(offset?: number): number;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readInt16LE(offset?: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readInt32BE(offset?: number): number;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readInt32LE(offset?: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readInt8(offset?: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readIntBE(offset: number,byteLength: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

@param byteLengthNumber of bytes to read. Must satisfy 0 .

readIntLE(offset: number,byteLength: number): number;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

@param byteLengthNumber of bytes to read. Must satisfy 0 .

readUint16BE(offset?: number): number;readUInt16BE(offset?: number): number;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readUint16LE(offset?: number): number;readUInt16LE(offset?: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readUint32BE(offset?: number): number;readUInt32BE(offset?: number): number;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readUint32LE(offset?: number): number;readUInt32LE(offset?: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readUint8(offset?: number): number;readUInt8(offset?: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

readUintBE(offset: number,byteLength: number): number;readUIntBE(offset: number,byteLength: number): number;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. @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

@param byteLengthNumber of bytes to read. Must satisfy 0 .

readUintLE(offset: number,byteLength: number): number;readUIntLE(offset: number,byteLength: number): number;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 @param offsetNumber of bytes to skip before starting to read. Must satisfy 0 .

@param byteLengthNumber of bytes to read. Must satisfy 0 .

reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: this) => number): number;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.

@param callbackfnA function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.

reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: this) => number,initialValue: number): number;reduceU>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: this) => U,initialValue: U): U;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.

@param callbackfnA function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.

@param initialValueIf 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.

reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: this) => number): number;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.

@param callbackfnA function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.

reduceRight(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: this) => number,initialValue: number): number;reduceRightU>(callbackfn: (previousValue: U, currentValue: number, currentIndex: number, array: this) => U,initialValue: U): U;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.

@param callbackfnA function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.

reverse(): this;Reverses the elements in an Array.

set(array: ArrayLikenumber>,offset?: number): void;Sets a value or an array of values.

@param arrayA typed or untyped array of values to set.

@param offsetThe index in the current array at which the values are to be written.

setFromBase64(base64: string,offset?: number): { read: number; written: number };Set the contents of the Uint8Array from a base64 encoded string

@param base64The base64 encoded string to decode into the array

@param offsetOptional starting index to begin setting the decoded bytes (default: 0)

setFromHex(hex: string): { read: number; written: number };Set the contents of the Uint8Array from a hex encoded string

@param hexThe hex encoded string to decode into the array. The string must have an even number of characters, be valid hexadecimal characters and contain no whitespace.

some(predicate: (value: number, index: number, array: this) => unknown,thisArg?: any): boolean;Determines whether the specified callback function returns true for any element of an array.

@param predicateA 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.

@param thisArgAn object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.

sort(compareFn?: (a: number, b: number) => number): this;Sorts an array.

@param compareFnFunction 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) subarray(start?: number,end?: number): BufferTArrayBuffer>;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).) @param startWhere the new Buffer will start.

@param endWhere the new Buffer will end (not inclusive).

buf1.swap16(); console.log(buf1); // Prints: 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: ```js 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. ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">swap16(): this;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: buf1.swap16(); console.log(buf1); // Prints: 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. @returnsA reference to buf.

buf1.swap32(); console.log(buf1); // Prints: const buf2 = Buffer.from([0x1, 0x2, 0x3]); buf2.swap32(); // Throws ERR_INVALID_BUFFER_SIZE. ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">swap32(): this;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: buf1.swap32(); console.log(buf1); // Prints: const buf2 = Buffer.from([0x1, 0x2, 0x3]); buf2.swap32(); // Throws ERR_INVALID_BUFFER_SIZE. @returnsA reference to buf.

buf1.swap64(); console.log(buf1); // Prints: const buf2 = Buffer.from([0x1, 0x2, 0x3]); buf2.swap64(); // Throws ERR_INVALID_BUFFER_SIZE. ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">swap64(): this;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: buf1.swap64(); console.log(buf1); // Prints: const buf2 = Buffer.from([0x1, 0x2, 0x3]); buf2.swap64(); // Throws ERR_INVALID_BUFFER_SIZE. @returnsA reference to buf.

toBase64(options?: { alphabet: 'base64' | 'base64url'; omitPadding: boolean }): string;Convert the Uint8Array to a base64 encoded string

@returnsThe base64 encoded string representation of the Uint8Array

toHex(): string;Convert the Uint8Array to a hex encoded string

@returnsThe hex encoded string representation of the Uint8Array

{ return value && value.type === 'Buffer' ? Buffer.from(value) : value; }); console.log(copy); // Prints: ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">toJSON(): { data: number[]; type: 'Buffer' };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: toLocaleString(): string;Converts a number to a string by using the current locale.

toLocaleString(locales: string | string[],options?: NumberFormatOptions): string;toReversed(): Uint8Array ArrayBuffer>;Copies the array and returns the copy with the elements in reverse order.

toSorted(compareFn?: (a: number, b: number) => number): Uint8Array ArrayBuffer>;Copies and sorts the array.

@param compareFnFunction used to determine the order of the elements. It is expected to return a negative value if the first argument is less than the second argument, zero if they're equal, and a positive value otherwise. If omitted, the elements are sorted in ascending order.

const myNums = Uint8Array.from([11, 2, 22, 1]); myNums.toSorted((a, b) => a - b) // Uint8Array(4) [1, 2, 11, 22] toString(encoding?: BufferEncoding,start?: number,end?: number): string;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 @param encodingThe character encoding to use.

@param startThe byte offset to start decoding at.

@param endThe byte offset to stop decoding at (not inclusive).

valueOf(): this;Returns the primitive value of the specified object.

values(): ArrayIteratornumber>;Returns an list of values in the array

with(index: number,value: number): Uint8Array ArrayBuffer>;Copies the array and inserts the given number at the provided index.

@param indexThe index of the value to overwrite. If the index is negative, then it replaces from the end of the array.

@param valueThe value to insert into the copied array.

@returnsA copy of the original array with the inserted value.

write(string: string,encoding?: BufferEncoding): number;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 @param stringString to write to buf.

@param encodingThe character encoding of string.

@returnsNumber of bytes written.

write(string: string,offset: number,encoding?: BufferEncoding): number;write(string: string,offset: number,length: number,encoding?: BufferEncoding): number; ```" data-algolia-static="false" data-algolia-merged="false" data-type="Method">writeBigInt64BE(value: bigint,offset?: number): number;Writes 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: @param valueNumber to be written to buf.

@param offsetNumber of bytes to skip before starting to write. Must satisfy: 0 .