base64.js

Yet another Base64 transcoder.

Install

1$ npm install --save js-base64

Usage

In Browser

Locally…

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

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

1<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…

1import { Base64 } from 'js-base64';

1// or if you prefer no Base64 namespace
2import { encode, decode } from 'js-base64';

or even remotely.

1<script type="module">
2// note jsdelivr.net does not automatically minify .mjs
3import { Base64 } from 'https://cdn.jsdelivr.net/npm/js-base64@3.7.7/base64.mjs';
4</script>

1<script type="module">
2// or if you prefer no Base64 namespace
3import { encode, decode } from 'https://cdn.jsdelivr.net/npm/js-base64@3.7.7/base64.mjs';
4</script>

node.js (commonjs)

1const {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.

1require=require('esm')(module);
2import {Base64} from 'js-base64';

SYNOPSIS

1let latin = 'dankogai';
2let utf8  = '小飼弾'
3let u8s   =  new Uint8Array([100,97,110,107,111,103,97,105]);
4Base64.encode(latin);             // ZGFua29nYWk=
5Base64.encode(latin, true);       // ZGFua29nYWk skips padding
6Base64.encodeURI(latin);          // ZGFua29nYWk
7Base64.btoa(latin);               // ZGFua29nYWk=
8Base64.btoa(utf8);                // raises exception
9Base64.fromUint8Array(u8s);       // ZGFua29nYWk=
10Base64.fromUint8Array(u8s, true); // ZGFua29nYW which is URI safe
11Base64.encode(utf8);              // 5bCP6aO85by+
12Base64.encode(utf8, true)         // 5bCP6aO85by-
13Base64.encodeURI(utf8);           // 5bCP6aO85by-

1Base64.decode(      'ZGFua29nYWk=');// dankogai
2Base64.decode(      'ZGFua29nYWk'); // dankogai
3Base64.atob(        'ZGFua29nYWk=');// dankogai
4Base64.atob(        '5bCP6aO85by+');// '小飼弾' which is nonsense
5Base64.toUint8Array('ZGFua29nYWk=');// u8s above
6Base64.decode(      '5bCP6aO85by+');// 小飼弾
7// note .decodeURI() is unnecessary since it accepts both flavors
8Base64.decode(      '5bCP6aO85by-');// 小飼弾

1Base64.isValid(0);      // false: 0 is not string
2Base64.isValid('');     // true: a valid Base64-encoded empty byte
3Base64.isValid('ZA=='); // true: a valid Base64-encoded 'd'
4Base64.isValid('Z A='); // true: whitespaces are okay
5Base64.isValid('ZA');   // true: padding ='s can be omitted
6Base64.isValid('++');   // true: can be non URL-safe
7Base64.isValid('--');   // true: or URL-safe
8Base64.isValid('+-');   // false: can't mix both

Built-in Extensions

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

1// you have to explicitly extend String.prototype
2Base64.extendString();
3// once extended, you can do the following
4'dankogai'.toBase64();        // ZGFua29nYWk=
5'小飼弾'.toBase64();           // 5bCP6aO85by+
6'小飼弾'.toBase64(true);       // 5bCP6aO85by-
7'小飼弾'.toBase64URI();        // 5bCP6aO85by- ab alias of .toBase64(true)
8'小飼弾'.toBase64URL();        // 5bCP6aO85by- an alias of .toBase64URI()
9'ZGFua29nYWk='.fromBase64();  // dankogai
10'5bCP6aO85by+'.fromBase64();  // 小飼弾
11'5bCP6aO85by-'.fromBase64();  // 小飼弾
12'5bCP6aO85by-'.toUint8Array();// u8s above

1// you have to explicitly extend Uint8Array.prototype
2Base64.extendUint8Array();
3// once extended, you can do the following
4u8s.toBase64();     // 'ZGFua29nYWk='
5u8s.toBase64URI();  // 'ZGFua29nYWk'
6u8s.toBase64URL();  // 'ZGFua29nYWk' an alias of .toBase64URI()

1// extend all at once
2Base64.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)