node:buffer

Buffer is a global and the same object as the Buffer export of node:buffer, which follows Node’s buffer.

Example

// buffer.mjs
const greeting = Buffer.from("héllo");
console.log(greeting.length, greeting.toString("hex"));
console.log(greeting.toString("base64"), Buffer.from("aMOpbGxv", "base64").toString());

const header = Buffer.alloc(4);
header.writeUInt32BE(0xcafebabe);
console.log(header.toString("hex"), header.readUInt16LE(2));
console.log(Buffer.concat([greeting, Buffer.from("!")]).toString());

utf-8 · js · Lines: 9

elide run buffer.mjs prints:

text

6 68c3a96c6c6f
aMOpbGxv héllo
cafebabe 48826
héllo!

utf-8 · text · Lines: 4

Differences from Node

Buffer.allocUnsafe and Buffer.allocUnsafeSlow return zero-filled memory.

Reference

Status: Full · 56 of 62 suite tests pass (90.3%) · since 1.1.0

Exports

Export	Kind	Status	Notes
`Buffer`	class	Full	`Buffer.alloc()`, `Buffer.allocUnsafe()`, `Buffer.allocUnsafeSlow()`, `Buffer.from()`, `Buffer.isBuffer()`, `Buffer.isEncoding()`, `Buffer.byteLength()`, `Buffer.concat()`, `Buffer.compare()`, `length`, `buffer`, `byteOffset`, `compare()`, `copy()`, `equals()`, `fill()`, `includes()`, `indexOf()`, `lastIndexOf()`, `slice()`, `subarray()`, `write()`, `toString()`, `toJSON()`, `readUInt8()`, `readUInt16BE()`, `readUInt16LE()`, `readUInt32BE()`, `readUInt32LE()`, `readInt8()`, `readInt16BE()`, `readInt16LE()`, `readInt32BE()`, `readInt32LE()`, `readUIntBE()`, `readUIntLE()`, `readIntBE()`, `readIntLE()`, `readFloatBE()`, `readFloatLE()`, `readDoubleBE()`, `readDoubleLE()`, `writeUInt8()`, `writeUInt16BE()`, `writeUInt16LE()`, `writeUInt32BE()`, `writeUInt32LE()`, `writeInt8()`, `writeInt16BE()`, `writeInt16LE()`, `writeInt32BE()`, `writeInt32LE()`, `writeUIntBE()`, `writeUIntLE()`, `writeIntBE()`, `writeIntLE()`, `writeFloatBE()`, `writeFloatLE()`, `writeDoubleBE()`, `writeDoubleLE()`, `swap16()`, `swap32()`, `swap64()`
`atob()`	function	Full	Decodes a base64-encoded ASCII string into a Latin-1 string
`btoa()`	function	Full	Encodes a Latin-1 string as base64 ASCII
`isAscii()`	function	Full	Returns true if every byte’s high bit is clear (the input contains only 7-bit ASCII)
`isUtf8()`	function	Full	Returns true if the bytes form a structurally valid UTF-8 sequence (no overlong forms, surrogates, or…
`kMaxLength`	property	Full	Largest buffer size representable as a 32-bit JS integer (2^31 - 1)
`kStringMaxLength`	property	Full	Largest string length the runtime will allocate (2^31 - 1)

Tests: node-api node:buffer: 56 pass, 6 fail, 0 error, 7 skipped. Failing: test-buffer-alloc.js, test-buffer-constructor-node-modules-paths.js, test-buffer-constructor-node-modules.js, test-buffer-constructor-outside-node-modules.js, test-buffer-indexof.js, test-buffer-pool-untransferable.js.