base64-js-1.2.0.js

(function(){
  'use strict'

  window.byteLength = byteLength
  window.toByteArray = toByteArray
  window.fromByteArray = fromByteArray

  var lookup = []
  var revLookup = []
  var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array

  var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
  for (var i = 0, len = code.length; i < len; ++i) {
    lookup[i] = code[i]
    revLookup[code.charCodeAt(i)] = i
  }

  revLookup['-'.charCodeAt(0)] = 62
  revLookup['_'.charCodeAt(0)] = 63

  function placeHoldersCount (b64) {
    var len = b64.length
    if (len % 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
    return b64[len - 2] === '=' ? 2 : b64[len - 1] === '=' ? 1 : 0
  }

  function byteLength (b64) {
    // base64 is 4/3 + up to two characters of the original data
    return b64.length * 3 / 4 - placeHoldersCount(b64)
  }

  function toByteArray (b64) {
    var i, j, l, tmp, placeHolders, arr
    var len = b64.length
    placeHolders = placeHoldersCount(b64)

    arr = new Arr(len * 3 / 4 - placeHolders)

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

    var L = 0

    for (i = 0, j = 0; i < l; i += 4, j += 3) {
      tmp = (revLookup[b64.charCodeAt(i)] << 18) | (revLookup[b64.charCodeAt(i + 1)] << 12) | (revLookup[b64.charCodeAt(i + 2)] << 6) | revLookup[b64.charCodeAt(i + 3)]
      arr[L++] = (tmp >> 16) & 0xFF
      arr[L++] = (tmp >> 8) & 0xFF
      arr[L++] = tmp & 0xFF
    }

    if (placeHolders === 2) {
      tmp = (revLookup[b64.charCodeAt(i)] << 2) | (revLookup[b64.charCodeAt(i + 1)] >> 4)
      arr[L++] = tmp & 0xFF
    } else if (placeHolders === 1) {
      tmp = (revLookup[b64.charCodeAt(i)] << 10) | (revLookup[b64.charCodeAt(i + 1)] << 4) | (revLookup[b64.charCodeAt(i + 2)] >> 2)
      arr[L++] = (tmp >> 8) & 0xFF
      arr[L++] = tmp & 0xFF
    }

    return arr
  }

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

  function encodeChunk (uint8, start, end) {
    var tmp
    var output = []
    for (var i = start; i < end; i += 3) {
      tmp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2])
      output.push(tripletToBase64(tmp))
    }
    return output.join('')
  }

  function fromByteArray (uint8) {
    var tmp
    var len = uint8.length
    var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
    var output = ''
    var parts = []
    var maxChunkLength = 16383 // must be multiple of 3

    // go through the array every three bytes, we'll deal with trailing stuff later
    for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
      parts.push(encodeChunk(uint8, i, (i + maxChunkLength) > len2 ? len2 : (i + maxChunkLength)))
    }

    // pad the end with zeros, but make sure to not forget the extra bytes
    if (extraBytes === 1) {
      tmp = uint8[len - 1]
      output += lookup[tmp >> 2]
      output += lookup[(tmp << 4) & 0x3F]
      output += '=='
    } else if (extraBytes === 2) {
      tmp = (uint8[len - 2] << 8) + (uint8[len - 1])
      output += lookup[tmp >> 10]
      output += lookup[(tmp >> 4) & 0x3F]
      output += lookup[(tmp << 2) & 0x3F]
      output += '='
    }

    parts.push(output)

    return parts.join('')
  }
})();