node__buffer.d.ts - Node

Usage in Deno

```typescript import * as mod from "node:node__buffer.d.ts"; ```

`Buffer` objects are used to represent a fixed-length sequence of bytes. Many Node.js APIs support `Buffer`s. The `Buffer` class is a subclass of JavaScript's [`Uint8Array`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array) class and extends it with methods that cover additional use cases. Node.js APIs accept plain [`Uint8Array`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array) s wherever `Buffer`s are supported as well. While the `Buffer` class is available within the global scope, it is still recommended to explicitly reference it via an import or require statement. ```js import { Buffer } from 'node:buffer'; // Creates a zero-filled Buffer of length 10. const buf1 = Buffer.alloc(10); // Creates a Buffer of length 10, // filled with bytes which all have the value `1`. const buf2 = Buffer.alloc(10, 1); // Creates an uninitialized buffer of length 10. // This is faster than calling Buffer.alloc() but the returned // Buffer instance might contain old data that needs to be // overwritten using fill(), write(), or other functions that fill the Buffer's // contents. const buf3 = Buffer.allocUnsafe(10); // Creates a Buffer containing the bytes [1, 2, 3]. const buf4 = Buffer.from([1, 2, 3]); // Creates a Buffer containing the bytes [1, 1, 1, 1] – the entries // are all truncated using `(value & 255)` to fit into the range 0–255. const buf5 = Buffer.from([257, 257.5, -255, '1']); // Creates a Buffer containing the UTF-8-encoded bytes for the string 'tést': // [0x74, 0xc3, 0xa9, 0x73, 0x74] (in hexadecimal notation) // [116, 195, 169, 115, 116] (in decimal notation) const buf6 = Buffer.from('tést'); // Creates a Buffer containing the Latin-1 bytes [0x74, 0xe9, 0x73, 0x74]. const buf7 = Buffer.from('tést', 'latin1'); ```

Classes

Blob

A [`Blob`](https://developer.mozilla.org/en-US/docs/Web/API/Blob) encapsulates immutable, raw data that can be safely shared across multiple worker threads.

File

A [`File`](https://developer.mozilla.org/en-US/docs/Web/API/File) provides information about files.

Functions

atob

Decodes a string of Base64-encoded data into bytes, and encodes those bytes into a string using Latin-1 (ISO-8859-1). The `data` may be any JavaScript-value that can be coerced into a string. **This function is only provided for compatibility with legacy web platform APIs** **and should never be used in new code, because they use strings to represent** **binary data and predate the introduction of typed arrays in JavaScript.** **For code running using Node.js APIs, converting between base64-encoded strings** **and binary data should be performed using `Buffer.from(str, 'base64')` and `buf.toString('base64')`.**

btoa

Decodes a string into bytes using Latin-1 (ISO-8859), and encodes those bytes into a string using Base64. The `data` may be any JavaScript-value that can be coerced into a string. **This function is only provided for compatibility with legacy web platform APIs** **and should never be used in new code, because they use strings to represent** **binary data and predate the introduction of typed arrays in JavaScript.** **For code running using Node.js APIs, converting between base64-encoded strings** **and binary data should be performed using `Buffer.from(str, 'base64')` and `buf.toString('base64')`.**

isAscii

This function returns `true` if `input` contains only valid ASCII-encoded data, including the case in which `input` is empty. Throws if the `input` is a detached array buffer.

isUtf8

This function returns `true` if `input` contains only valid UTF-8-encoded data, including the case in which `input` is empty. Throws if the `input` is a detached array buffer.

resolveObjectURL

Resolves a `'blob:nodedata:...'` an associated `Blob` object registered using a prior call to `URL.createObjectURL()`.

transcode

Re-encodes the given `Buffer` or `Uint8Array` instance from one character encoding to another. Returns a new `Buffer` instance. Throws if the `fromEnc` or `toEnc` specify invalid character encodings or if conversion from `fromEnc` to `toEnc` is not permitted. Encodings supported by `buffer.transcode()` are: `'ascii'`, `'utf8'`, `'utf16le'`, `'ucs2'`, `'latin1'`, and `'binary'`. The transcoding process will use substitution characters if a given byte sequence cannot be adequately represented in the target encoding. For instance: ```js import { Buffer, transcode } from 'node:buffer'; const newBuf = transcode(Buffer.from('€'), 'utf8', 'ascii'); console.log(newBuf.toString('ascii')); // Prints: '?' ``` Because the Euro (`€`) sign is not representable in US-ASCII, it is replaced with `?` in the transcoded `Buffer`.