utf8 utf16 in javascript

gistfile1.js

  /**
             * Convert a UTF16 string to UTF8.
             * @param {String} input
             * @returns {String}
             */
            utf16To8: function (input) {
                var _unescape = function(s) {
                    function d(x, n) {
                        return String.fromCharCode(parseInt(n, 16));
                    }
                    return s.replace(/%([0-9A-F]{2})/ig, d);
                };
                try{
                    return _unescape(encodeURIComponent(input));
                }catch (URIError) {
                    //include invalid character, cannot convert
                    return input;
                }
            },
            /**
             * Convert a UTF8 string to UTF16.
             * @param {String} input
             * @returns {String}
             */
            utf8To16: function (input) {
                var _escape = function(s) {
                    function q(c) {
                        c = c.charCodeAt();
                        return '%' + (c<16 ? '0' : '') + c.toString(16).toUpperCase();
                    }
                    return s.replace(/[\x00-),:-?[-^`{-\xFF]/g, q);
                };
                try{
                    return decodeURIComponent(_escape(input));
                }catch (URIError) {
                    //include invalid character, cannot convert
                    return input;
                }
            },
            
 
 /**
             * Actually is utf16 string in js to utf8 byte array
             *
             * @param str
             * @returns {Array}
             */
            __stringToArray : function (str) {
                var utf8 = [];
                for (var i=0; i < str.length; i++) {
                    var charcode = str.charCodeAt(i);
                    if (charcode < 0x80) utf8.push(charcode);
                    else if (charcode < 0x800) {
                        utf8.push(0xc0 | (charcode >> 6),
                            0x80 | (charcode & 0x3f));
                    }
                    else if (charcode < 0xd800 || charcode >= 0xe000) {
                        utf8.push(0xe0 | (charcode >> 12),
                            0x80 | ((charcode>>6) & 0x3f),
                            0x80 | (charcode & 0x3f));
                    }
                    // surrogate pair
                    else {
                        i++;
                        // UTF-16 encodes 0x10000-0x10FFFF by
                        // subtracting 0x10000 and splitting the
                        // 20 bits of 0x0-0xFFFFF into two halves
                        charcode = 0x10000 + (((charcode & 0x3ff)<<10)
                        | (str.charCodeAt(i) & 0x3ff))
                        utf8.push(0xf0 | (charcode >>18),
                            0x80 | ((charcode>>12) & 0x3f),
                            0x80 | ((charcode>>6) & 0x3f),
                            0x80 | (charcode & 0x3f));
                    }
                }
                return utf8;
            },
            /**
             * Actually from utf8 byte array to utf16 string in js
             * @param input
             * @returns {string}
             */
            __arrayToString: function (input) {
                var i, str = '';

                for (i = 0; i < input.length; i++) {
                    str += '%' + ('0' + input[i].toString(16)).slice(-2);
                }
                str = decodeURIComponent(str);
                return str;
            },