javascript base64

gistfile1.js

var base64 = (function () {
    var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

    var obj = {
        /**
         * Encodes a string in base64
         * @param {String} input The string to encode in base64.
         */
        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);
            } while (i < input.length);

            return output;
        },

        /**
         * Decodes a base64 string.
         * @param {String} input The string to decode.
         */
        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 =
            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);
                }
            } while (i < input.length);

            return output;
        }
    };

    return obj;
})();