dankogai/js-base64

$ npm install --save js-base64

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

<script src="https://cdn.jsdelivr.net/npm/[email protected]/base64.min.js"></script>

import { Base64 } from 'js-base64';

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

<script type="module">
// note jsdelivr.net does not automatically minify .mjs
import { Base64 } from 'https://cdn.jsdelivr.net/npm/[email protected]/base64.mjs';
</script>

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

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

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

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); // ZGFua29nYWk 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('Z');    // false: a single character can't encode a byte
Base64.isValid('++');   // true: can be non URL-safe
Base64.isValid('--');   // true: or URL-safe
Base64.isValid('+-');   // false: can't mix both

const bytes = new Uint8Array([251, 255]);
Base64.fromUint8Array(bytes);       // '+/8='
Base64.fromUint8Array(bytes, true); // '-_8'
Base64.toUint8Array('+/8=');        // Uint8Array [251, 255]
Base64.toUint8Array('-_8');         // Uint8Array [251, 255]

// 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- an 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();// UTF-8 bytes of '小飼弾'

// 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()

var pngBase64 = 
  "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII=";