Base64 Function for JS

b64.js

/*
Copyright Vassilis Petroulias [DRDigit]

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
var B64 = {
    alphabet: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=',
    lookup: null,
    ie: /MSIE /.test(navigator.userAgent),
    ieo: /MSIE [67]/.test(navigator.userAgent),
    encode: function (s) {
        var buffer = B64.toUtf8(s),
            position = -1,
            len = buffer.length,
            nan1, nan2, enc = [, , , ];
        if (B64.ie) {
            var result = [];
            while (++position < len) {
                nan1 = buffer[position + 1], nan2 = buffer[position + 2];
                enc[0] = buffer[position] >> 2;
                enc[1] = ((buffer[position] & 3) << 4) | (buffer[++position] >> 4);
                if (isNaN(nan1)) enc[2] = enc[3] = 64;
                else {
                    enc[2] = ((buffer[position] & 15) << 2) | (buffer[++position] >> 6);
                    enc[3] = (isNaN(nan2)) ? 64 : buffer[position] & 63;
                }
                result.push(B64.alphabet[enc[0]], B64.alphabet[enc[1]], B64.alphabet[enc[2]], B64.alphabet[enc[3]]);
            }
            return result.join('');
        } else {
            result = '';
            while (++position < len) {
                nan1 = buffer[position + 1], nan2 = buffer[position + 2];
                enc[0] = buffer[position] >> 2;
                enc[1] = ((buffer[position] & 3) << 4) | (buffer[++position] >> 4);
                if (isNaN(nan1)) enc[2] = enc[3] = 64;
                else {
                    enc[2] = ((buffer[position] & 15) << 2) | (buffer[++position] >> 6);
                    enc[3] = (isNaN(nan2)) ? 64 : buffer[position] & 63;
                }
                result += B64.alphabet[enc[0]] + B64.alphabet[enc[1]] + B64.alphabet[enc[2]] + B64.alphabet[enc[3]];
            }
            return result;
        }
    },
    decode: function (s) {
        var buffer = B64.fromUtf8(s),
            position = 0,
            len = buffer.length;
        if (B64.ieo) {
            result = [];
            while (position < len) {
                if (buffer[position] < 128) result.push(String.fromCharCode(buffer[position++]));
                else if (buffer[position] > 191 && buffer[position] < 224) result.push(String.fromCharCode(((buffer[position++] & 31) << 6) | (buffer[position++] & 63)));
                else result.push(String.fromCharCode(((buffer[position++] & 15) << 12) | ((buffer[position++] & 63) << 6) | (buffer[position++] & 63)));
            }
            return result.join('');
        } else {
            result = '';
            while (position < len) {
                if (buffer[position] < 128) result += String.fromCharCode(buffer[position++]);
                else if (buffer[position] > 191 && buffer[position] < 224) result += String.fromCharCode(((buffer[position++] & 31) << 6) | (buffer[position++] & 63));
                else result += String.fromCharCode(((buffer[position++] & 15) << 12) | ((buffer[position++] & 63) << 6) | (buffer[position++] & 63));
            }
            return result;
        }
    },
    toUtf8: function (s) {
        var position = -1,
            len = s.length,
            chr, buffer = [];
        if (/^[\x00-\x7f]*$/.test(s)) while (++position < len)
        buffer.push(s.charCodeAt(position));
        else while (++position < len) {
            chr = s.charCodeAt(position);
            if (chr < 128) buffer.push(chr);
            else if (chr < 2048) buffer.push((chr >> 6) | 192, (chr & 63) | 128);
            else buffer.push((chr >> 12) | 224, ((chr >> 6) & 63) | 128, (chr & 63) | 128);
        }
        return buffer;
    },
    fromUtf8: function (s) {
        var position = -1,
            len, buffer = [],
            enc = [, , , ];
        if (!B64.lookup) {
            len = B64.alphabet.length;
            B64.lookup = {};
            while (++position < len)
            B64.lookup[B64.alphabet[position]] = position;
            position = -1;
        }
        len = s.length;
        while (position < len) {
            enc[0] = B64.lookup[s.charAt(++position)];
            enc[1] = B64.lookup[s.charAt(++position)];
            buffer.push((enc[0] << 2) | (enc[1] >> 4));
            enc[2] = B64.lookup[s.charAt(++position)];
            if (enc[2] == 64) break;
            buffer.push(((enc[1] & 15) << 4) | (enc[2] >> 2));
            enc[3] = B64.lookup[s.charAt(++position)];
            if (enc[3] == 64) break;
            buffer.push(((enc[2] & 3) << 6) | enc[3]);
        }
        return buffer;
    }
};