b64.js

/**
@license The MIT License (MIT)
Copyright (c) 2014 Jameson Little
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
*/
var lookup = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'

;(function (exports) {
  'use strict'

  var Arr = (typeof Uint8Array !== 'undefined')
    ? Uint8Array
    : Array

  var PLUS = '+'.charCodeAt(0)
  var SLASH = '/'.charCodeAt(0)
  var NUMBER = '0'.charCodeAt(0)
  var LOWER = 'a'.charCodeAt(0)
  var UPPER = 'A'.charCodeAt(0)
  var PLUS_URL_SAFE = '-'.charCodeAt(0)
  var SLASH_URL_SAFE = '_'.charCodeAt(0)

  function decode (elt) {
    var code = elt.charCodeAt(0)
    if (code === PLUS || code === PLUS_URL_SAFE) return 62 // '+'
    if (code === SLASH || code === SLASH_URL_SAFE) return 63 // '/'
    if (code < NUMBER) return -1 // no match
    if (code < NUMBER + 10) return code - NUMBER + 26 + 26
    if (code < UPPER + 26) return code - UPPER
    if (code < LOWER + 26) return code - LOWER + 26
  }

  function b64ToByteArray (b64) {
    var i, j, l, tmp, placeHolders, arr

    if (b64.length % 4 > 0) {
      throw new Error('Invalid string. Length must be a multiple of 4')
    }

    // the number of equal signs (place holders)
    // if there are two placeholders, than the two characters before it
    // represent one byte
    // if there is only one, then the three characters before it represent 2 bytes
    // this is just a cheap hack to not do indexOf twice
    var len = b64.length
    placeHolders = b64.charAt(len - 2) === '=' ? 2 : b64.charAt(len - 1) === '=' ? 1 : 0

    // base64 is 4/3 + up to two characters of the original data
    arr = new Arr(b64.length * 3 / 4 - placeHolders)

    // if there are placeholders, only get up to the last complete 4 chars
    l = placeHolders > 0 ? b64.length - 4 : b64.length

    var L = 0

    function push (v) {
      arr[L++] = v
    }

    for (i = 0, j = 0; i < l; i += 4, j += 3) {
      tmp = (decode(b64.charAt(i)) << 18) | (decode(b64.charAt(i + 1)) << 12) | (decode(b64.charAt(i + 2)) << 6) | decode(b64.charAt(i + 3))
      push((tmp & 0xFF0000) >> 16)
      push((tmp & 0xFF00) >> 8)
      push(tmp & 0xFF)
    }

    if (placeHolders === 2) {
      tmp = (decode(b64.charAt(i)) << 2) | (decode(b64.charAt(i + 1)) >> 4)
      push(tmp & 0xFF)
    } else if (placeHolders === 1) {
      tmp = (decode(b64.charAt(i)) << 10) | (decode(b64.charAt(i + 1)) << 4) | (decode(b64.charAt(i + 2)) >> 2)
      push((tmp >> 8) & 0xFF)
      push(tmp & 0xFF)
    }

    return arr
  }

  function uint8ToBase64 (uint8) {
    var i
    var extraBytes = uint8.length % 3 // if we have 1 byte left, pad 2 bytes
    var output = ''
    var temp, length

    function encode (num) {
      return lookup.charAt(num)
    }

    function tripletToBase64 (num) {
      return encode(num >> 18 & 0x3F) + encode(num >> 12 & 0x3F) + encode(num >> 6 & 0x3F) + encode(num & 0x3F)
    }

    // go through the array every three bytes, we'll deal with trailing stuff later
    for (i = 0, length = uint8.length - extraBytes; i < length; i += 3) {
      temp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2])
      output += tripletToBase64(temp)
    }

    // pad the end with zeros, but make sure to not forget the extra bytes
    switch (extraBytes) {
      case 1:
        temp = uint8[uint8.length - 1]
        output += encode(temp >> 2)
        output += encode((temp << 4) & 0x3F)
        output += '=='
        break
      case 2:
        temp = (uint8[uint8.length - 2] << 8) + (uint8[uint8.length - 1])
        output += encode(temp >> 10)
        output += encode((temp >> 4) & 0x3F)
        output += encode((temp << 2) & 0x3F)
        output += '='
        break
      default:
        break
    }

    return output
  }

  exports.toByteArray = b64ToByteArray
  exports.fromByteArray = uint8ToBase64
}((this.base64js = {})))