js-base64

What is js-base64?

The js-base64 npm package is a simple, fast, and consistent library for encoding and decoding to and from Base64, a group of binary-to-text encoding schemes that represent binary data in an ASCII string format by translating it into a radix-64 representation. It can be used in both browser and Node.js environments.

What are js-base64's main functionalities?

Encoding to Base64

This feature allows you to encode a string into Base64 format.

const { Base64 } = require('js-base64');
const encoded = Base64.encode('Hello, World!');
console.log(encoded); // Outputs: SGVsbG8sIFdvcmxkIQ==

Decoding from Base64

This feature allows you to decode a Base64 encoded string back to its original format.

const { Base64 } = require('js-base64');
const decoded = Base64.decode('SGVsbG8sIFdvcmxkIQ==');
console.log(decoded); // Outputs: Hello, World!

Safe URL Base64 Encoding and Decoding

This feature provides methods for encoding and decoding Base64 in a URL-safe manner, which means it can be used in URL query parameters without needing additional encoding.

const { Base64 } = require('js-base64');
const urlEncoded = Base64.encodeURI('https://www.example.com/?search=js-base64');
console.log(urlEncoded); // Outputs a URL-safe Base64 string
const urlDecoded = Base64.decode(urlEncoded);
console.log(urlDecoded); // Outputs the original URL

No Padding Option

This feature allows you to encode in Base64 without any padding characters ('='), which might be necessary in certain contexts where padding is not supported or desired.

const { Base64 } = require('js-base64');
const noPaddingEncoded = Base64.encode('Hello, World!', true); // The second argument indicates no padding
console.log(noPaddingEncoded); // Outputs: SGVsbG8sIFdvcmxkIQ

Other packages similar to js-base64

btoa

The btoa package provides a polyfill for the btoa() function, which converts binary data to a Base64-encoded string. It is primarily intended for use in environments where the window.btoa function is not available, such as Node.js. It does not offer decoding functionality.

atob

The atob package is the counterpart to btoa, providing a polyfill for the atob() function, which decodes a Base64-encoded string. Like btoa, it is intended for environments where the window.atob function is not available, and it only offers decoding functionality.

base64-js

The base64-js package provides functions to encode and decode Base64 in a way that is highly compatible with the browser's built-in btoa and atob functions. It is designed to be more efficient by working with Typed Arrays, making it suitable for performance-critical applications that handle binary data.

buffer

The buffer package is a Node.js module that provides additional functionalities for manipulating binary data. It includes methods for encoding and decoding Base64 as part of its API. While it is more comprehensive than js-base64, it is also more complex and Node.js specific.

README

base64.js

Yet another Base64 transcoder.

Install

$ npm install --save js-base64

Usage

In Browser

Locally…

<script src="base64.js"></script>

… or Directly from CDN. In which case you don't even need to install.

<script src="https://cdn.jsdelivr.net/npm/js-base64@3.7.7/base64.min.js"></script>

This good old way loads Base64 in the global context (window). Though Base64.noConflict() is made available, you should consider using ES6 Module to avoid tainting window.

As an ES6 Module

locally…

import { Base64 } from 'js-base64';

// or if you prefer no Base64 namespace
import { encode, decode } from 'js-base64';

or even remotely.

<script type="module">
// note jsdelivr.net does not automatically minify .mjs
import { Base64 } from 'https://cdn.jsdelivr.net/npm/js-base64@3.7.7/base64.mjs';
</script>

<script type="module">
// or if you prefer no Base64 namespace
import { encode, decode } from 'https://cdn.jsdelivr.net/npm/js-base64@3.7.7/base64.mjs';
</script>

node.js (commonjs)

const {Base64} = require('js-base64');

Unlike the case above, the global context is no longer modified.

You can also use esm to import instead of require.

require=require('esm')(module);
import {Base64} from 'js-base64';

SYNOPSIS

let latin = 'dankogai';
let utf8  = '小飼弾'
let u8s   =  new Uint8Array([100,97,110,107,111,103,97,105]);
Base64.encode(latin);             // ZGFua29nYWk=
Base64.encode(latin, true);       // ZGFua29nYWk skips padding
Base64.encodeURI(latin);          // ZGFua29nYWk
Base64.btoa(latin);               // ZGFua29nYWk=
Base64.btoa(utf8);                // raises exception
Base64.fromUint8Array(u8s);       // ZGFua29nYWk=
Base64.fromUint8Array(u8s, true); // ZGFua29nYW which is URI safe
Base64.encode(utf8);              // 5bCP6aO85by+
Base64.encode(utf8, true)         // 5bCP6aO85by-
Base64.encodeURI(utf8);           // 5bCP6aO85by-

Base64.decode(      'ZGFua29nYWk=');// dankogai
Base64.decode(      'ZGFua29nYWk'); // dankogai
Base64.atob(        'ZGFua29nYWk=');// dankogai
Base64.atob(        '5bCP6aO85by+');// '小飼弾' which is nonsense
Base64.toUint8Array('ZGFua29nYWk=');// u8s above
Base64.decode(      '5bCP6aO85by+');// 小飼弾
// note .decodeURI() is unnecessary since it accepts both flavors
Base64.decode(      '5bCP6aO85by-');// 小飼弾

Base64.isValid(0);      // false: 0 is not string
Base64.isValid('');     // true: a valid Base64-encoded empty byte
Base64.isValid('ZA=='); // true: a valid Base64-encoded 'd'
Base64.isValid('Z A='); // true: whitespaces are okay
Base64.isValid('ZA');   // true: padding ='s can be omitted
Base64.isValid('++');   // true: can be non URL-safe
Base64.isValid('--');   // true: or URL-safe
Base64.isValid('+-');   // false: can't mix both

Built-in Extensions

By default Base64 leaves built-in prototypes untouched. But you can extend them as below.

// you have to explicitly extend String.prototype
Base64.extendString();
// once extended, you can do the following
'dankogai'.toBase64();        // ZGFua29nYWk=
'小飼弾'.toBase64();           // 5bCP6aO85by+
'小飼弾'.toBase64(true);       // 5bCP6aO85by-
'小飼弾'.toBase64URI();        // 5bCP6aO85by- ab alias of .toBase64(true)
'小飼弾'.toBase64URL();        // 5bCP6aO85by- an alias of .toBase64URI()
'ZGFua29nYWk='.fromBase64();  // dankogai
'5bCP6aO85by+'.fromBase64();  // 小飼弾
'5bCP6aO85by-'.fromBase64();  // 小飼弾
'5bCP6aO85by-'.toUint8Array();// u8s above

// you have to explicitly extend Uint8Array.prototype
Base64.extendUint8Array();
// once extended, you can do the following
u8s.toBase64();     // 'ZGFua29nYWk='
u8s.toBase64URI();  // 'ZGFua29nYWk'
u8s.toBase64URL();  // 'ZGFua29nYWk' an alias of .toBase64URI()

// extend all at once
Base64.extendBuiltins()

.decode() vs .atob (and .encode() vs btoa())

Suppose you have:

var pngBase64 = 
  "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII=";

Which is a Base64-encoded 1x1 transparent PNG, DO NOT USE Base64.decode(pngBase64).  Use Base64.atob(pngBase64) instead.  Base64.decode() decodes to UTF-8 string while Base64.atob() decodes to bytes, which is compatible to browser built-in atob() (Which is absent in node.js).  The same rule applies to the opposite direction.

Or even better, Base64.toUint8Array(pngBase64).

Brief History

• Since version 3.3 it is written in TypeScript. Now base64.mjs is compiled from base64.ts then base64.js is generated from base64.mjs.
• Since version 3.7 base64.js is ES5-compatible again (hence IE11-compatible).
• Since 3.0 js-base64 switch to ES2015 module so it is no longer compatible with legacy browsers like IE (see above)