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

    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;
  }
};