libbase64

Encode and decode base64 strings. Written in TypeScript, published with both ES module and CommonJS builds and type declarations. Requires Node.js 20 or newer.

Usage

Install with npm

npm install libbase64

Require in your script

const libbase64 = require('libbase64');

or import it as an ES module

import libbase64 from 'libbase64';
// or
import { encode, decode, wrap, Encoder, Decoder } from 'libbase64';

Encode values

Encode Buffer objects or unicode strings with

libbase64.encode(val) → String

Where

• val is a Buffer, an Uint8Array or an unicode string

Example

libbase64.encode('jõgeva');
// asO1Z2V2YQ==

Decode values

Decode base64 strings to a Buffer with

libbase64.decode(str) → Buffer

Where

• str is a base64 encoded string. Line breaks and other characters outside of the base64 alphabet are ignored. Input made of several separately padded segments (eg. every line padded on its own) is decoded segment by segment

Example

libbase64.decode('asO1Z2V2YQ==').toString();
// jõgeva

Wrap encoded values

To enforce soft line breaks on lines longer than selected amount of characters, use wrap

libbase64.wrap(str[, lineLength]) → String

Where

• str is a base64 encoded string
• lineLength (defaults to 76) is the maximum allowed line length

Example

libbase64.wrap('asO1Z2V2asO1Z2V2asO1Z2V2YQ==', 10);
// asO1Z2V2as\r\n
// O1Z2V2asO1\r\n
// Z2V2YQ==

Transform Streams

libbase64 makes it possible to encode and decode streams with libbase64.Encoder and libbase64.Decoder constructors.

Encoder Stream

Create new Encoder Stream with

const encoder = new libbase64.Encoder([options])

Where

• options is the optional stream options object
• options.lineLength (Number) if you want to use any other line length than the default 76 characters (or set to false to turn the soft wrapping off completely)
• options.skipStartBytes (Number) Optional. How many bytes to skip from output (default to 0)
• options.limitOutputBytes (Number) Optional. How many bytes to return (defaults to all bytes). The misspelled limitOutbutBytes that earlier versions documented is still accepted
• options.startPadding (String) Optional. Fills first line with provided padding string. Usually goes together with skipStartBytes to get line folding correct.

The output is the same as libbase64.wrap(libbase64.encode(input), lineLength), no matter how the input is split into chunks.

Example

The following example script reads in a file, encodes it to base64 and saves the output to a file.

const libbase64 = require('libbase64');
const fs = require('fs');
const source = fs.createReadStream('source.txt');
const encoded = fs.createWriteStream('encoded.txt');
const encoder = new libbase64.Encoder();

source.pipe(encoder).pipe(encoded);

Decoder Stream

Create new Decoder Stream with

const decoder = new libbase64.Decoder([options])

Where

• options is the optional stream options object

Example

The following example script reads in a file in base64 encoding, decodes it and saves the output to a file.

const libbase64 = require('libbase64');
const fs = require('fs');
const encoded = fs.createReadStream('encoded.txt');
const dest = fs.createWriteStream('dest.txt');
const decoder = new libbase64.Decoder();

encoded.pipe(decoder).pipe(dest);

License

MIT