Buffer

Properties

BYTES_PER_ELEMENTnumberRequired

The size in bytes of each element in the array.

[toStringTag]"Uint8Array"Required

bufferArrayBufferLikeRequired

The ArrayBuffer instance referenced by the array.

byteLengthnumberRequired

The length in bytes of the array.

byteOffsetnumberRequired

The offset in bytes of the array.

lengthnumberRequired

The length of the array.

Methods

[iterator]

**[iterator]**(): [IterableIterator](/references/services/interfaces/IterableIterator)<number>

Returns

IterableIterator<number>

IterableIteratorIterableIterator<number>Required

at

**at**(index): undefined \| number

Returns the item located at the specified index.

Parameters

indexnumberRequired

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

Returns

undefined | number

undefined \| numberundefined | number

compare

**compare**(target, targetStart?, targetEnd?, sourceStart?, sourceEnd?): 0\|1\|-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 buf
1 is returned if target should come _before_buf when sorted.
-1 is returned if target should come _after_buf 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 sourceEndarguments can be used to limit the comparison to specific ranges within targetand 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.

Parameters

targetUint8ArrayRequired

A Buffer or Uint8Array with which to compare buf.

targetStartnumber

The offset within target at which to begin comparison.

targetEndnumber

The offset within target at which to end comparison (not inclusive).

sourceStartnumber

The offset within buf at which to begin comparison.

sourceEndnumber

The offset within buf at which to end comparison (not inclusive).

Returns

0 | 1 | -1

`0` \| `1` \| `-1`0 | 1 | -1

Since

v0.11.13

copy

**copy**(target, targetStart?, sourceStart?, sourceEnd?): 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

Parameters

targetUint8ArrayRequired

A Buffer or Uint8Array to copy into.

targetStartnumber

The offset within target at which to begin writing.

sourceStartnumber

The offset within buf from which to begin copying.

sourceEndnumber

The offset within buf at which to stop copying (not inclusive).

Returns

number

numbernumber

The number of bytes copied.

Since

v0.1.90

copyWithin

**copyWithin**(target, start, end?): [Buffer](/references/services/#buffer)

Returns the this object after copying a section of the array identified by start and end to the same array starting at position target

Parameters

targetnumberRequired

If target is negative, it is treated as length+target where length is the length of the array.

startnumberRequired

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

endnumber

If not specified, length of the this object is used as its default value.

Returns

Buffer

BufferBufferRequired

entries

**entries**(): [IterableIterator](/references/services/interfaces/IterableIterator)<[number, number]>

Creates and returns an iterator of [index, byte] pairs from the contents of buf.

import { Buffer } from 'node:buffer';

// Log the entire contents of a `Buffer`.

const buf = Buffer.from('buffer');

for (const pair of buf.entries()) {
  console.log(pair);
}
// Prints:
//   [0, 98]
//   [1, 117]
//   [2, 102]
//   [3, 102]
//   [4, 101]
//   [5, 114]

Returns

IterableIterator<[number, number]>

IterableIteratorIterableIterator<[number, number]>Required

Since

v1.1.0

equals

**equals**(otherBuffer): 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

Parameters

otherBufferUint8ArrayRequired

A Buffer or Uint8Array with which to compare buf.

Returns

boolean

booleanboolean

Since

v0.11.13

every

**every**(predicate, thisArg?): boolean

Determines whether all the members of an array satisfy the specified test.

Parameters

predicate(value: number, index: number, array: Uint8Array) => unknownRequired

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.

thisArgany

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

Returns

boolean

booleanboolean

fill

**fill**(value, offset?, end?, encoding?): [Buffer](/references/services/#buffer)

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.

Parameters

valuestring | number | Uint8ArrayRequired

The value with which to fill buf. Empty value (string, Uint8Array, Buffer) is coerced to 0.

offsetnumber

Number of bytes to skip before starting to fill buf.

endnumber

Where to stop filling buf (not inclusive).

encodingBufferEncoding

The encoding for value if value is a string.

Returns

Buffer

BufferBufferRequired

A reference to buf.

Since

v0.5.0

filter

**filter**(predicate, thisArg?): Uint8Array

Returns the elements of an array that meet the condition specified in a callback function.

Parameters

predicate(value: number, index: number, array: Uint8Array) => anyRequired

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

thisArgany

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

Returns

Uint8Array

Uint8ArrayUint8ArrayRequired

find

**find**(predicate, thisArg?): undefined \| number

Returns the value of the first element in the array where predicate is true, and undefined otherwise.

Parameters

predicate(value: number, index: number, obj: Uint8Array) => booleanRequired

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.

thisArgany

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

Returns

undefined | number

undefined \| numberundefined | number

findIndex

**findIndex**(predicate, thisArg?): number

Returns the index of the first element in the array where predicate is true, and -1 otherwise.

Parameters

predicate(value: number, index: number, obj: Uint8Array) => booleanRequired

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.

thisArgany

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

Returns

number

numbernumber

findLast

**findLast**<TypeParameter S>(predicate, thisArg?): undefined \| S

Returns the value of the last element in the array where predicate is true, and undefined otherwise.

SnumberRequired

Parameters

predicate(value: number, index: number, array: Uint8Array) => value is SRequired

findLast 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.

thisArgany

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

Returns

undefined | S

undefined \| Sundefined | S

**findLast**(predicate, thisArg?): undefined \| number

Parameters

predicate(value: number, index: number, array: Uint8Array) => unknownRequired

thisArgany

Returns

undefined | number

undefined \| numberundefined | number

findLastIndex

**findLastIndex**(predicate, thisArg?): number

Returns the index of the last element in the array where predicate is true, and -1 otherwise.

Parameters

predicate(value: number, index: number, array: Uint8Array) => unknownRequired

findLastIndex 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.

thisArgany

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

Returns

number

numbernumber

forEach

**forEach**(callbackfn, thisArg?): void

Performs the specified action for each element in an array.

Parameters

callbackfn(value: number, index: number, array: Uint8Array) => voidRequired

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

thisArgany

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

Returns

void

voidvoid

includes

**includes**(value, byteOffset?, encoding?): 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

Parameters

valuestring | number | BufferRequired

What to search for.

byteOffsetnumber

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

encodingBufferEncoding

If value is a string, this is its encoding.

Returns

boolean

booleanboolean

true if value was found in buf, false otherwise.

Since

v5.3.0

indexOf

**indexOf**(value, byteOffset?, encoding?): number

If value is:

a string, value is interpreted according to the character encoding inencoding.
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 aTypeError. 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.

Parameters

valuestring | number | Uint8ArrayRequired

What to search for.

byteOffsetnumber

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

encodingBufferEncoding

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

Returns

number

numbernumber

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

Since

v1.5.0

join

**join**(separator?): string

Adds all the elements of an array separated by the specified separator string.

Parameters

separatorstring

A 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

string

stringstring

keys

**keys**(): [IterableIterator](/references/services/interfaces/IterableIterator)<number>

Creates and returns an iterator of buf keys (indices).

import { Buffer } from 'node:buffer';

const buf = Buffer.from('buffer');

for (const key of buf.keys()) {
  console.log(key);
}
// Prints:
//   0
//   1
//   2
//   3
//   4
//   5

Returns

IterableIterator<number>

IterableIteratorIterableIterator<number>Required

Since

v1.1.0

lastIndexOf

**lastIndexOf**(value, byteOffset?, encoding?): 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 aTypeError. 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.

Parameters

valuestring | number | Uint8ArrayRequired

What to search for.

byteOffsetnumber

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

encodingBufferEncoding

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

Returns

number

numbernumber

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

Since

v6.0.0

map

**map**(callbackfn, thisArg?): Uint8Array

Calls a defined callback function on each element of an array, and returns an array that contains the results.

Parameters

callbackfn(value: number, index: number, array: Uint8Array) => numberRequired

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

thisArgany

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

Returns

Uint8Array

Uint8ArrayUint8ArrayRequired

readBigInt64BE

**readBigInt64BE**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.

Returns

bigint

bigintbigint

Since

v12.0.0, v10.20.0

readBigInt64LE

**readBigInt64LE**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.

Returns

bigint

bigintbigint

Since

v12.0.0, v10.20.0

readBigUInt64BE

**readBigUInt64BE**(offset?): 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

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.

Returns

bigint

bigintbigint

Since

v12.0.0, v10.20.0

readBigUInt64LE

**readBigUInt64LE**(offset?): 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

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.

Returns

bigint

bigintbigint

Since

v12.0.0, v10.20.0

readBigUint64BE

**readBigUint64BE**(offset?): bigint

Parameters

offsetnumber

Returns

bigint

bigintbigint

Alias

Buffer.readBigUInt64BE

Since

v14.10.0, v12.19.0

readBigUint64LE

**readBigUint64LE**(offset?): bigint

Parameters

offsetnumber

Returns

bigint

bigintbigint

Alias

Buffer.readBigUInt64LE

Since

v14.10.0, v12.19.0

readDoubleBE

**readDoubleBE**(offset?): 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

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8.

Returns

number

numbernumber

Since

v0.11.15

readDoubleLE

**readDoubleLE**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8.

Returns

number

numbernumber

Since

v0.11.15

readFloatBE

**readFloatBE**(offset?): 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

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

Since

v0.11.15

readFloatLE

**readFloatLE**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

Since

v0.11.15

readInt16BE

**readInt16BE**(offset?): 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

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.

Returns

number

numbernumber

Since

v0.5.5

readInt16LE

**readInt16LE**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.

Returns

number

numbernumber

Since

v0.5.5

readInt32BE

**readInt32BE**(offset?): 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

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

Since

v0.5.5

readInt32LE

**readInt32LE**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

Since

v0.5.5

readInt8

**readInt8**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1.

Returns

number

numbernumber

Since

v0.5.0

readIntBE

**readIntBE**(offset, byteLength): number

Reads byteLength number of bytes from buf at the specified offsetand 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.

Parameters

offsetnumberRequired

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.

byteLengthnumberRequired

Number of bytes to read. Must satisfy 0 < byteLength <= 6.

Returns

number

numbernumber

Since

v0.11.15

readIntLE

**readIntLE**(offset, byteLength): number

Reads byteLength number of bytes from buf at the specified offsetand 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

Parameters

offsetnumberRequired

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.

byteLengthnumberRequired

Number of bytes to read. Must satisfy 0 < byteLength <= 6.

Returns

number

numbernumber

Since

v0.11.15

readUInt16BE

**readUInt16BE**(offset?): 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

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.

Returns

number

numbernumber

Since

v0.5.5

readUInt16LE

**readUInt16LE**(offset?): number

Reads an unsigned, little-endian 16-bit integer from buf at the specifiedoffset.

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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.

Returns

number

numbernumber

Since

v0.5.5

readUInt32BE

**readUInt32BE**(offset?): 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

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

Since

v0.5.5

readUInt32LE

**readUInt32LE**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

Since

v0.5.5

readUInt8

**readUInt8**(offset?): 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.

Parameters

offsetnumber

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1.

Returns

number

numbernumber

Since

v0.5.0

readUIntBE

**readUIntBE**(offset, byteLength): number

Reads byteLength number of bytes from buf at the specified offsetand 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.

Parameters

offsetnumberRequired

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.

byteLengthnumberRequired

Number of bytes to read. Must satisfy 0 < byteLength <= 6.

Returns

number

numbernumber

Since

v0.11.15

readUIntLE

**readUIntLE**(offset, byteLength): number

Reads byteLength number of bytes from buf at the specified offsetand 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

Parameters

offsetnumberRequired

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.

byteLengthnumberRequired

Number of bytes to read. Must satisfy 0 < byteLength <= 6.

Returns

number

numbernumber

Since

v0.11.15

readUint16BE

**readUint16BE**(offset?): number

Parameters

offsetnumber

Returns

number

numbernumber

Alias

Buffer.readUInt16BE

Since

v14.9.0, v12.19.0

readUint16LE

**readUint16LE**(offset?): number

Parameters

offsetnumber

Returns

number

numbernumber

Alias

Buffer.readUInt16LE

Since

v14.9.0, v12.19.0

readUint32BE

**readUint32BE**(offset?): number

Parameters

offsetnumber

Returns

number

numbernumber

Alias

Buffer.readUInt32BE

Since

v14.9.0, v12.19.0

readUint32LE

**readUint32LE**(offset?): number

Parameters

offsetnumber

Returns

number

numbernumber

Alias

Buffer.readUInt32LE

Since

v14.9.0, v12.19.0

readUint8

**readUint8**(offset?): number

Parameters

offsetnumber

Returns

number

numbernumber

Alias

Buffer.readUInt8

Since

v14.9.0, v12.19.0

readUintBE

**readUintBE**(offset, byteLength): number

Parameters

offsetnumberRequired

byteLengthnumberRequired

Returns

number

numbernumber

Alias

Buffer.readUIntBE

Since

v14.9.0, v12.19.0

readUintLE

**readUintLE**(offset, byteLength): number

Parameters

offsetnumberRequired

byteLengthnumberRequired

Returns

number

numbernumber

Alias

Buffer.readUIntLE

Since

v14.9.0, v12.19.0

reduce

**reduce**(callbackfn): 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.

Parameters

callbackfn(previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => numberRequired

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

Returns

number

numbernumber

**reduce**(callbackfn, initialValue): number

Parameters

callbackfn(previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => numberRequired

initialValuenumberRequired

Returns

number

numbernumber

**reduce**<TypeParameter U>(callbackfn, initialValue): U

UobjectRequired

Parameters

callbackfn(previousValue: U, currentValue: number, currentIndex: number, array: Uint8Array) => URequired

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

initialValueURequired

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.

Returns

U

reduceRight

**reduceRight**(callbackfn): 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.

Parameters

callbackfn(previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => numberRequired

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

Returns

number

numbernumber

**reduceRight**(callbackfn, initialValue): number

Parameters

callbackfn(previousValue: number, currentValue: number, currentIndex: number, array: Uint8Array) => numberRequired

initialValuenumberRequired

Returns

number

numbernumber

**reduceRight**<TypeParameter U>(callbackfn, initialValue): U

UobjectRequired

Parameters

callbackfn(previousValue: U, currentValue: number, currentIndex: number, array: Uint8Array) => URequired

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

initialValueURequired

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.

Returns

U

reverse

**reverse**(): [Buffer](/references/services/#buffer)

Returns

Buffer

BufferBufferRequired

set

**set**(array, offset?): void

Sets a value or an array of values.

Parameters

arrayArrayLike<number>Required

A typed or untyped array of values to set.

offsetnumber

The index in the current array at which the values are to be written.

Returns

void

voidvoid

slice

**slice**(start?, end?): [Buffer](/references/services/#buffer)

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 (!)

Parameters

startnumber

Where the new Buffer will start.

endnumber

Where the new Buffer will end (not inclusive).

Returns

Buffer

BufferBufferRequired

Since

v0.3.0

Deprecated

Use subarray instead.

some

**some**(predicate, thisArg?): boolean

Determines whether the specified callback function returns true for any element of an array.

Parameters

predicate(value: number, index: number, array: Uint8Array) => unknownRequired

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.

thisArgany

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

Returns

boolean

booleanboolean

sort

**sort**(compareFn?): [Buffer](/references/services/#buffer)

Sorts an array.

Parameters

compareFn(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. ts [11,2,22,1].sort((a, b) => a - b)

Returns

Buffer

BufferBufferRequired

subarray

**subarray**(start?, end?): [Buffer](/references/services/#buffer)

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).)

Parameters

startnumber

Where the new Buffer will start.

endnumber

Where the new Buffer will end (not inclusive).

Returns

Buffer

BufferBufferRequired

Since

v3.0.0

swap16

**swap16**(): [Buffer](/references/services/#buffer)

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.

Returns

Buffer

BufferBufferRequired

A reference to buf.

Since

v5.10.0

swap32

**swap32**(): [Buffer](/references/services/#buffer)

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.

Returns

Buffer

BufferBufferRequired

A reference to buf.

Since

v5.10.0

swap64

**swap64**(): [Buffer](/references/services/#buffer)

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.

Returns

Buffer

BufferBufferRequired

A reference to buf.

Since

v6.3.0

toJSON

**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 &#x26;&#x26; value.type === 'Buffer' ?
    Buffer.from(value) :
    value;
});

console.log(copy);
// Prints: <Buffer 01 02 03 04 05>

Returns

object

objectobject

datanumber[]Required

type"Buffer"Required

Since

v0.9.2

toLocaleString

**toLocaleString**(): string

Converts a number to a string by using the current locale.

Returns

string

stringstring

toReversed

**toReversed**(): Uint8Array

Copies the array and returns the copy with the elements in reverse order.

Returns

Uint8Array

Uint8ArrayUint8ArrayRequired

toSorted

**toSorted**(compareFn?): Uint8Array

Copies and sorts the array.

Parameters

compareFn(a: number, b: number) => number

Function 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, ASCII character order. ts const myNums = Uint8Array.from([11, 2, 22, 1]); myNums.toSorted((a, b) => a - b) // Uint8Array(4) [1, 2, 11, 22]

Returns

Uint8Array

Uint8ArrayUint8ArrayRequired

toString

**toString**(encoding?, start?, end?): 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

Parameters

encodingBufferEncoding

The character encoding to use.

startnumber

The byte offset to start decoding at.

endnumber

The byte offset to stop decoding at (not inclusive).

Returns

string

stringstring

Since

v0.1.90

valueOf

**valueOf**(): Uint8Array

Returns the primitive value of the specified object.

Returns

Uint8Array

Uint8ArrayUint8ArrayRequired

values

**values**(): [IterableIterator](/references/services/interfaces/IterableIterator)<number>

Creates and returns an iterator for buf values (bytes). This function is called automatically when a Buffer is used in a for..of statement.

import { Buffer } from 'node:buffer';

const buf = Buffer.from('buffer');

for (const value of buf.values()) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

for (const value of buf) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

Returns

IterableIterator<number>

IterableIteratorIterableIterator<number>Required

Since

v1.1.0

with

**with**(index, value): Uint8Array

Copies the array and inserts the given number at the provided index.

Parameters

indexnumberRequired

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

valuenumberRequired

The value to insert into the copied array.

Returns

Uint8Array

Uint8ArrayUint8ArrayRequired

A copy of the original array with the inserted value.

write

**write**(string, encoding?): 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

Parameters

stringstringRequired

String to write to buf.

encodingBufferEncoding

The character encoding of string.

Returns

number

numbernumber

Number of bytes written.

Since

v0.1.90

**write**(string, offset, encoding?): number

Parameters

stringstringRequired

offsetnumberRequired

encodingBufferEncoding

Returns

number

numbernumber

**write**(string, offset, length, encoding?): number

Parameters

stringstringRequired

offsetnumberRequired

lengthnumberRequired

encodingBufferEncoding

Returns

number

numbernumber

writeBigInt64BE

**writeBigInt64BE**(value, offset?): 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: <Buffer 01 02 03 04 05 06 07 08>

Parameters

valuebigintRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v12.0.0, v10.20.0

writeBigInt64LE

**writeBigInt64LE**(value, offset?): number

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>

Parameters

valuebigintRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v12.0.0, v10.20.0

writeBigUInt64BE

**writeBigUInt64BE**(value, offset?): number

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>

Parameters

valuebigintRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v12.0.0, v10.20.0

writeBigUInt64LE

**writeBigUInt64LE**(value, offset?): number

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.

Parameters

valuebigintRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v12.0.0, v10.20.0

writeBigUint64BE

**writeBigUint64BE**(value, offset?): number

Parameters

valuebigintRequired

offsetnumber

Returns

number

numbernumber

Alias

Buffer.writeBigUInt64BE

Since

v14.10.0, v12.19.0

writeBigUint64LE

**writeBigUint64LE**(value, offset?): number

Parameters

valuebigintRequired

offsetnumber

Returns

number

numbernumber

Alias

Buffer.writeBigUInt64LE

Since

v14.10.0, v12.19.0

writeDoubleBE

**writeDoubleBE**(value, offset?): number

Writes value to buf at the specified offset as big-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.11.15

writeDoubleLE

**writeDoubleLE**(value, offset?): number

Writes value to buf at the specified offset as little-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.11.15

writeFloatBE

**writeFloatBE**(value, offset?): number

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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.11.15

writeFloatLE

**writeFloatLE**(value, offset?): number

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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.11.15

writeInt16BE

**writeInt16BE**(value, offset?): number

Writes value to buf at the specified offset as big-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeInt16LE

**writeInt16LE**(value, offset?): number

Writes value to buf at the specified offset as little-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeInt32BE

**writeInt32BE**(value, offset?): number

Writes value to buf at the specified offset as big-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeInt32LE

**writeInt32LE**(value, offset?): number

Writes value to buf at the specified offset as little-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeInt8

**writeInt8**(value, offset?): number

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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.0

writeIntBE

**writeIntBE**(value, offset, byteLength): number

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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumberRequired

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.

byteLengthnumberRequired

Number of bytes to write. Must satisfy 0 < byteLength <= 6.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.11.15

writeIntLE

**writeIntLE**(value, offset, byteLength): number

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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumberRequired

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.

byteLengthnumberRequired

Number of bytes to write. Must satisfy 0 < byteLength <= 6.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.11.15

writeUInt16BE

**writeUInt16BE**(value, offset?): number

Writes value to buf at the specified offset as big-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeUInt16LE

**writeUInt16LE**(value, offset?): number

Writes value to buf at the specified offset as little-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeUInt32BE

**writeUInt32BE**(value, offset?): number

Writes value to buf at the specified offset as big-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeUInt32LE

**writeUInt32LE**(value, offset?): number

Writes value to buf at the specified offset as little-endian. The valuemust 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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeUInt8

**writeUInt8**(value, offset?): number

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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumber

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.0

writeUIntBE

**writeUIntBE**(value, offset, byteLength): number

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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumberRequired

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.

byteLengthnumberRequired

Number of bytes to write. Must satisfy 0 < byteLength <= 6.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeUIntLE

**writeUIntLE**(value, offset, byteLength): number

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>

Parameters

valuenumberRequired

Number to be written to buf.

offsetnumberRequired

Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.

byteLengthnumberRequired

Number of bytes to write. Must satisfy 0 < byteLength <= 6.

Returns

number

numbernumber

offset plus the number of bytes written.

Since

v0.5.5

writeUint16BE

**writeUint16BE**(value, offset?): number

Parameters

valuenumberRequired

offsetnumber

Returns

number

numbernumber

Alias

Buffer.writeUInt16BE

Since

v14.9.0, v12.19.0

writeUint16LE

**writeUint16LE**(value, offset?): number

Parameters

valuenumberRequired

offsetnumber

Returns

number

numbernumber

Alias

Buffer.writeUInt16LE

Since

v14.9.0, v12.19.0

writeUint32BE

**writeUint32BE**(value, offset?): number

Parameters

valuenumberRequired

offsetnumber

Returns

number

numbernumber

Alias

Buffer.writeUInt32BE

Since

v14.9.0, v12.19.0

writeUint32LE

**writeUint32LE**(value, offset?): number

Parameters

valuenumberRequired

offsetnumber

Returns

number

numbernumber

Alias

Buffer.writeUInt32LE

Since

v14.9.0, v12.19.0

writeUint8

**writeUint8**(value, offset?): number

Parameters

valuenumberRequired

offsetnumber

Returns

number

numbernumber

Alias

Buffer.writeUInt8

Since

v14.9.0, v12.19.0

writeUintBE

**writeUintBE**(value, offset, byteLength): number

Parameters

valuenumberRequired

offsetnumberRequired

byteLengthnumberRequired

Returns

number

numbernumber

Alias

Buffer.writeUIntBE

Since

v14.9.0, v12.19.0

writeUintLE

**writeUintLE**(value, offset, byteLength): number

Parameters

valuenumberRequired

offsetnumberRequired

byteLengthnumberRequired

Returns

number

numbernumber

Alias

Buffer.writeUIntLE

Since

v14.9.0, v12.19.0

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Properties​

Methods​

[iterator]​

Returns​

at​

Parameters​

Returns​

compare​

Parameters​

Returns​

Since​

copy​

Parameters​

Returns​

Since​

copyWithin​

Parameters​

Returns​

entries​

Returns​

Since​

equals​

Parameters​

Returns​

Since​

every​

Parameters​

Returns​

fill​

Parameters​

Returns​

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filter​

Parameters​

Returns​

find​

Parameters​

Returns​

findIndex​

Parameters​

Returns​

findLast​

Parameters​

Returns​

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Returns​

findLastIndex​

Parameters​

Returns​

forEach​

Parameters​

Returns​

includes​

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Returns​

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indexOf​

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Returns​

Since​

join​

Parameters​

Returns​

keys​

Returns​

Since​

lastIndexOf​

Parameters​

Returns​

Since​

map​

Parameters​

Returns​

readBigInt64BE​

Parameters​

Returns​

Since​

readBigInt64LE​

Parameters​

Returns​

Properties

Methods

[iterator]

Returns

at

Parameters

Returns

compare

Parameters

Returns

Since

copy

Parameters

Returns

Since

copyWithin

Parameters

Returns

entries

Returns

Since

equals

Parameters

Returns

Since

every

Parameters

Returns

fill

Parameters

Returns

Since

filter

Parameters

Returns

find

Parameters

Returns

findIndex

Parameters

Returns

findLast

Parameters

Returns

Parameters

Returns

findLastIndex

Parameters

Returns

forEach

Parameters

Returns

includes

Parameters

Returns

Since

indexOf

Parameters

Returns

Since

join

Parameters

Returns

keys

Returns

Since

lastIndexOf

Parameters

Returns

Since

map

Parameters

Returns

readBigInt64BE

Parameters

Returns

Since

readBigInt64LE

Parameters

Returns