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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]​

Returns​

IterableIteratorIterableIterator<number>Required

at​

Takes an integer value and returns the item at that index, allowing for positive and negative integers. Negative integers count back from the last item in the array.

Parameters​

indexnumberRequired

Returns​

undefined \| numberundefined | number

compare​

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 \| -10 | 1 | -1

Since​

v0.11.13

copy​

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​

numbernumber
The number of bytes copied.

Since​

v0.1.90

copyWithin​

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​

BufferBufferRequired

entries​

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​

IterableIteratorIterableIterator<[number, number]>Required

Since​

v1.1.0

equals​

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​

booleanboolean

Since​

v0.11.13

every​

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​

booleanboolean

fill​

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 &#x26; 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​

BufferBufferRequired
A reference to buf.

Since​

v0.5.0

filter​

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​

Uint8ArrayUint8ArrayRequired

find​

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 \| numberundefined | number

findIndex​

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​

numbernumber

forEach​

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​

voidvoid

includes​

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​

booleanboolean
true if value was found in buf, false otherwise.

Since​

v5.3.0

indexOf​

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​

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

Since​

v1.5.0

join​

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​

stringstring

keys​

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​

IterableIteratorIterableIterator<number>Required

Since​

v1.1.0

lastIndexOf​

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​

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

Since​

v6.0.0

map​

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​

Uint8ArrayUint8ArrayRequired

readBigInt64BE​

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​

bigintbigint

Since​

v12.0.0, v10.20.0

readBigInt64LE​

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​

bigintbigint

Since​

v12.0.0, v10.20.0

readBigUInt64BE​

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​

bigintbigint

Since​

v12.0.0, v10.20.0

readBigUInt64LE​

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​

bigintbigint

Since​

v12.0.0, v10.20.0

readBigUint64BE​

Parameters​

offsetnumber

Returns​

bigintbigint

Alias​

Buffer.readBigUInt64BE

Since​

v14.10.0, v12.19.0

readBigUint64LE​

Parameters​

offsetnumber

Returns​

bigintbigint

Alias​

Buffer.readBigUInt64LE

Since​

v14.10.0, v12.19.0

readDoubleBE​

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​

numbernumber

Since​

v0.11.15

readDoubleLE​

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​

numbernumber

Since​

v0.11.15

readFloatBE​

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​

numbernumber

Since​

v0.11.15

readFloatLE​

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​

numbernumber

Since​

v0.11.15

readInt16BE​

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​

numbernumber

Since​

v0.5.5

readInt16LE​

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​

numbernumber

Since​

v0.5.5

readInt32BE​

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​

numbernumber

Since​

v0.5.5

readInt32LE​

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​

numbernumber

Since​

v0.5.5

readInt8​

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​

numbernumber

Since​

v0.5.0

readIntBE​

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​

numbernumber

Since​

v0.11.15

readIntLE​

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​

numbernumber

Since​

v0.11.15

readUInt16BE​

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​

numbernumber

Since​

v0.5.5

readUInt16LE​

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​

numbernumber

Since​

v0.5.5

readUInt32BE​

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​

numbernumber

Since​

v0.5.5

readUInt32LE​

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​

numbernumber

Since​

v0.5.5

readUInt8​

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​

numbernumber

Since​

v0.5.0

readUIntBE​

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​

numbernumber

Since​

v0.11.15

readUIntLE​

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​

numbernumber

Since​

v0.11.15

readUint16BE​

Parameters​

offsetnumber

Returns​

numbernumber

Alias​

Buffer.readUInt16BE

Since​

v14.9.0, v12.19.0

readUint16LE​

Parameters​

offsetnumber

Returns​

numbernumber

Alias​

Buffer.readUInt16LE

Since​

v14.9.0, v12.19.0

readUint32BE​

Parameters​

offsetnumber

Returns​

numbernumber

Alias​

Buffer.readUInt32BE

Since​

v14.9.0, v12.19.0

readUint32LE​

Parameters​

offsetnumber

Returns​

numbernumber

Alias​

Buffer.readUInt32LE

Since​

v14.9.0, v12.19.0

readUint8​

Parameters​

offsetnumber

Returns​

numbernumber

Alias​

Buffer.readUInt8

Since​

v14.9.0, v12.19.0

readUintBE​

Parameters​

offsetnumberRequired
byteLengthnumberRequired

Returns​

numbernumber

Alias​

Buffer.readUIntBE

Since​

v14.9.0, v12.19.0

readUintLE​

Parameters​

offsetnumberRequired
byteLengthnumberRequired

Returns​

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​

numbernumber

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

Parameters​

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

Returns​

numbernumber

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

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​

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​

numbernumber

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

Parameters​

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

Returns​

numbernumber

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

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​

reverse​

Returns​

BufferBufferRequired

set​

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​

voidvoid

slice​

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​

BufferBufferRequired

Since​

v0.3.0

Deprecated​

Use subarray instead.

some​

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​

booleanboolean

sort​

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​

BufferBufferRequired

subarray​

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​

BufferBufferRequired

Since​

v3.0.0

swap16​

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​

BufferBufferRequired
A reference to buf.

Since​

v5.10.0

swap32​

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​

BufferBufferRequired
A reference to buf.

Since​

v5.10.0

swap64​

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​

BufferBufferRequired
A reference to buf.

Since​

v6.3.0

toJSON​

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​

objectobject
datanumber[]Required
type"Buffer"Required

Since​

v0.9.2

toLocaleString​

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

Returns​

stringstring

toString​

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​

stringstring

Since​

v0.1.90

valueOf​

Returns the primitive value of the specified object.

Returns​

Uint8ArrayUint8ArrayRequired

values​

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​

IterableIteratorIterableIterator<number>Required

Since​

v1.1.0

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​

numbernumber
Number of bytes written.

Since​

v0.1.90

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

Parameters​

stringstringRequired
offsetnumberRequired
encodingBufferEncoding

Returns​

numbernumber

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

Parameters​

stringstringRequired
offsetnumberRequired
lengthnumberRequired
encodingBufferEncoding

Returns​

numbernumber

writeBigInt64BE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v12.0.0, v10.20.0

writeBigInt64LE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v12.0.0, v10.20.0

writeBigUInt64BE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v12.0.0, v10.20.0

writeBigUInt64LE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v12.0.0, v10.20.0

writeBigUint64BE​

Parameters​

valuebigintRequired
offsetnumber

Returns​

numbernumber

Alias​

Buffer.writeBigUInt64BE

Since​

v14.10.0, v12.19.0

writeBigUint64LE​

Parameters​

valuebigintRequired
offsetnumber

Returns​

numbernumber

Alias​

Buffer.writeBigUInt64LE

Since​

v14.10.0, v12.19.0

writeDoubleBE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.11.15

writeDoubleLE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.11.15

writeFloatBE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.11.15

writeFloatLE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.11.15

writeInt16BE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeInt16LE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeInt32BE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeInt32LE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeInt8​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.0

writeIntBE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.11.15

writeIntLE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.11.15

writeUInt16BE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeUInt16LE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeUInt32BE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeUInt32LE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeUInt8​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.0

writeUIntBE​

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeUIntLE​

Writes byteLength bytes of value to buf at the specified offsetas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than an unsigned integer.

This function is also available under the writeUintLE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeUIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>

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​

numbernumber
offset plus the number of bytes written.

Since​

v0.5.5

writeUint16BE​

Parameters​

valuenumberRequired
offsetnumber

Returns​

numbernumber

Alias​

Buffer.writeUInt16BE

Since​

v14.9.0, v12.19.0

writeUint16LE​

Parameters​

valuenumberRequired
offsetnumber

Returns​

numbernumber

Alias​

Buffer.writeUInt16LE

Since​

v14.9.0, v12.19.0

writeUint32BE​

Parameters​

valuenumberRequired
offsetnumber

Returns​

numbernumber

Alias​

Buffer.writeUInt32BE

Since​

v14.9.0, v12.19.0

writeUint32LE​

Parameters​

valuenumberRequired
offsetnumber

Returns​

numbernumber

Alias​

Buffer.writeUInt32LE

Since​

v14.9.0, v12.19.0

writeUint8​

Parameters​

valuenumberRequired
offsetnumber

Returns​

numbernumber

Alias​

Buffer.writeUInt8

Since​

v14.9.0, v12.19.0

writeUintBE​

Parameters​

valuenumberRequired
offsetnumberRequired
byteLengthnumberRequired

Returns​

numbernumber

Alias​

Buffer.writeUIntBE

Since​

v14.9.0, v12.19.0

writeUintLE​

Parameters​

valuenumberRequired
offsetnumberRequired
byteLengthnumberRequired

Returns​

numbernumber

Alias​

Buffer.writeUIntLE

Since​

v14.9.0, v12.19.0

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