srv.base64.js

app.factory('base64', function () {
  'use strict';

  var keyStr = 'ABCDEFGHIJKLMNOP' +
    'QRSTUVWXYZabcdef' +
    'ghijklmnopqrstuv' +
    'wxyz0123456789+/' +
    '=';
  return {
    encode: function (input) {
      var output = '';
      var chr1, chr2, chr3 = '';
      var enc1, enc2, enc3, enc4 = '';
      var i = 0;

      do {
        chr1 = input.charCodeAt(i++);
        chr2 = input.charCodeAt(i++);
        chr3 = input.charCodeAt(i++);

        enc1 = chr1 >> 2;
        enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
        enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
        enc4 = chr3 & 63;

        if (isNaN(chr2)) {
          enc3 = enc4 = 64;
        } else if (isNaN(chr3)) {
          enc4 = 64;
        }

        output = output +
          keyStr.charAt(enc1) +
          keyStr.charAt(enc2) +
          keyStr.charAt(enc3) +
          keyStr.charAt(enc4);
        chr1 = chr2 = chr3 = '';
        enc1 = enc2 = enc3 = enc4 = '';
      } while (i < input.length);

      return output;
    },

    decode: function (input) {
      var output = '';
      var chr1, chr2, chr3 = '';
      var enc1, enc2, enc3, enc4 = '';
      var i = 0;

      // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
      var base64test = /[^A-Za-z0-9\+\/\=]/g;
      if (base64test.exec(input)) {
        console.log('There were invalid base64 characters in the input text.\n' +
          'Valid base64 characters are A-Z, a-z, 0-9, "+", "/",and "="\n' +
          'Expect errors in decoding.');
      }
      input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '');
      do {
        enc1 = keyStr.indexOf(input.charAt(i++));
        enc2 = keyStr.indexOf(input.charAt(i++));
        enc3 = keyStr.indexOf(input.charAt(i++));
        enc4 = keyStr.indexOf(input.charAt(i++));

        chr1 = (enc1 << 2) | (enc2 >> 4);
        chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
        chr3 = ((enc3 & 3) << 6) | enc4;

        output = output + String.fromCharCode(chr1);

        if (enc3 != 64) {
          output = output + String.fromCharCode(chr2);
        }
        if (enc4 != 64) {
          output = output + String.fromCharCode(chr3);
        }
        chr1 = chr2 = chr3 = '';
        enc1 = enc2 = enc3 = enc4 = '';

      } while (i < input.length);

      return output;
    }
  };
});