Javascript unserialize : Variable handling : PHP functions in JavaScript JAVASCRIPT TUTORIALS

function unserialize(data){
    // Takes a string representation of variable and recreates it  
    // 
    // version: 810.114
    // discuss at: http://phpjs.org/functions/unserialize
    // +     original by: Arpad Ray (mailto:arpad@php.net)
    // +     improved by: Pedro Tainha (http://www.pedrotainha.com)
    // +     bugfixed by: dptr1988
    // +      revised by: d3x
    // +     improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // %            note: We feel the main purpose of this function should be to ease the transport of data between php & js
    // %            note: Aiming for PHP-compatibility, we have to translate objects to arrays 
    // *       example 1: unserialize('a:3:{i:0;s:5:"Kevin";i:1;s:3:"van";i:2;s:9:"Zonneveld";}');
    // *       returns 1: ['Kevin', 'van', 'Zonneveld']
    // *       example 2: unserialize('a:3:{s:9:"firstName";s:5:"Kevin";s:7:"midName";s:3:"van";s:7:"surName";s:9:"Zonneveld";}');
    // *       returns 2: {firstName: 'Kevin', midName: 'van', surName: 'Zonneveld'}
    
    var error = function (type, msg, filename, line){throw new window[type](msg, filename, line);};
    var read_until = function (data, offset, stopchr){
        var buf = [];
        var chr = data.slice(offset, offset + 1);
        var i = 2;
        while(chr != stopchr){
            if((i+offset) > data.length){
                error('Error', 'Invalid');
            }
            buf.push(chr);
            chr = data.slice(offset + (i - 1),offset + i);
            i += 1;
        }
        return [buf.length, buf.join('')];
    };
    var read_chrs = function (data, offset, length){
        buf = [];
        for(var i = 0;i < length;i++){
            var chr = data.slice(offset + (i - 1),offset + i);
            buf.push(chr);
        }
        return [buf.length, buf.join('')];
    };
    var _unserialize = function (data, offset){
        if(!offset) offset = 0;
        var buf = [];
        var dtype = (data.slice(offset, offset + 1)).toLowerCase();
        
        var dataoffset = offset + 2;
        var typeconvert = new Function('x', 'return x');
        var chrs = 0;
        var datalength = 0;
        
        switch(dtype){
            case "i":
                typeconvert = new Function('x', 'return parseInt(x)');
                var readData = read_until(data, dataoffset, ';');
                var chrs = readData[0];
                var readdata = readData[1];
                dataoffset += chrs + 1;
            break;
            case "b":
                typeconvert = new Function('x', 'return (parseInt(x) == 1)');
                var readData = read_until(data, dataoffset, ';');
                var chrs = readData[0];
                var readdata = readData[1];
                dataoffset += chrs + 1;
            break;
            case "d":
                typeconvert = new Function('x', 'return parseFloat(x)');
                var readData = read_until(data, dataoffset, ';');
                var chrs = readData[0];
                var readdata = readData[1];
                dataoffset += chrs + 1;
            break;
            case "n":
                readdata = null;
            break;
            case "s":
                var ccount = read_until(data, dataoffset, ':');
                var chrs = ccount[0];
                var stringlength = ccount[1];
                dataoffset += chrs + 2;
                
                var readData = read_chrs(data, dataoffset+1, parseInt(stringlength));
                var chrs = readData[0];
                var readdata = readData[1];
                dataoffset += chrs + 2;
                if(chrs != parseInt(stringlength) && chrs != readdata.length){
                    error('SyntaxError', 'String length mismatch');
                }
            break;
            case "a":
                var readdata = {};
                
                var keyandchrs = read_until(data, dataoffset, ':');
                var chrs = keyandchrs[0];
                var keys = keyandchrs[1];
                dataoffset += chrs + 2;
                
                for(var i = 0;i < parseInt(keys);i++){
                    var kprops = _unserialize(data, dataoffset);
                    var kchrs = kprops[1];
                    var key = kprops[2];
                    dataoffset += kchrs;
                    
                    var vprops = _unserialize(data, dataoffset);
                    var vchrs = vprops[1];
                    var value = vprops[2];
                    dataoffset += vchrs;
                    
                    readdata[key] = value;
                }
                
                dataoffset += 1;
            break;
            default:
                error('SyntaxError', 'Unknown / Unhandled data type(s): ' + dtype);
            break;
        }
        return [dtype, dataoffset - offset, typeconvert(readdata)];
    };
    return _unserialize(data, 0)[2];
}