Base64.js

var Base64 = {
  // private property
  _keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

  // public method for encoding
  encode : function (input) {
      var output = "";
      var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
      var i = 0;

      input = Base64._utf8_encode(input);

      while (i < input.length) {

          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 +
          this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
          this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);

      }

      return output;
  },

  // public method for decoding
  decode : function (input) {
      var output = "";
      var chr1, chr2, chr3;
      var enc1, enc2, enc3, enc4;
      var i = 0;

      input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

      while (i < input.length) {

          enc1 = this._keyStr.indexOf(input.charAt(i++));
          enc2 = this._keyStr.indexOf(input.charAt(i++));
          enc3 = this._keyStr.indexOf(input.charAt(i++));
          enc4 = this._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);
          }

      }

      output = Base64._utf8_decode(output);

      return output;

  },

  // private method for UTF-8 encoding
  _utf8_encode : function (string) {
      string = string.replace(/\r\n/g,"\n");
      var utftext = "";

      for (var n = 0; n < string.length; n++) {

          var c = string.charCodeAt(n);

          if (c < 128) {
              utftext += String.fromCharCode(c);
          }
          else if((c > 127) && (c < 2048)) {
              utftext += String.fromCharCode((c >> 6) | 192);
              utftext += String.fromCharCode((c & 63) | 128);
          }
          else {
              utftext += String.fromCharCode((c >> 12) | 224);
              utftext += String.fromCharCode(((c >> 6) & 63) | 128);
              utftext += String.fromCharCode((c & 63) | 128);
          }

      }

      return utftext;
  },

  // private method for UTF-8 decoding
  _utf8_decode : function (utftext) {
      var string = "";
      var i = 0;
      var c = c1 = c2 = 0;

      while ( i < utftext.length ) {

          c = utftext.charCodeAt(i);

          if (c < 128) {
              string += String.fromCharCode(c);
              i++;
          }
          else if((c > 191) && (c < 224)) {
              c2 = utftext.charCodeAt(i+1);
              string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
              i += 2;
          }
          else {
              c2 = utftext.charCodeAt(i+1);
              c3 = utftext.charCodeAt(i+2);
              string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
              i += 3;
          }

      }

      return string;
  }
};

module.exports = Base64;