jQuery.deparam(): parse query string params into object.

jquery.deparam.js

/**
 * jQuery.deparam()
 * @author Sujeet Kumar <sujeetkv90@gmail.com> https://github.com/sujeetkv
 * 
 * @param string queryString (params string)
 * @param boolean coerce (force type conversion)
 */

(function ($) {
    
    $.deparam = function (queryString, coerce) {
        queryString = ('' + queryString).replace(/^\?/, '');
        
        var re = /([^&=]+)=?([^&]*)/g,
            m,
            params = {},
            coerceTypes = {'true': !0, 'false': !1, 'null': null},
            decode = function (str) {
                return decodeURIComponent(str.replace(/\+/g, '%20'));
            };
        
        if (queryString) {
            while (m = re.exec(queryString)) {
                var k = decode(m[1]),
                    v = decode(m[2]),
                    curr = params;
                
                if (coerce) {
                    v = !isNaN(v) ? +v : (v === 'undefined' ? undefined : (coerceTypes[v] ? coerceTypes[v] : v));
                }
                
                var keys = k.split('][');
                var keysLast = keys.length - 1;
                
                if (/\[/.test(keys[0]) && /\]$/.test(keys[keysLast])) {
                    keys[keysLast] = keys[keysLast].replace(/\]$/, '');
                    keys = keys.shift().split('[').concat(keys);
                    keysLast = keys.length - 1;
                }
                
                if (keysLast) {
                    for (var i = 0; i <= keysLast; i++) {
                        k = (keys[i] === '') ? curr.length : keys[i];
                        curr = curr[k] = (i < keysLast) ? curr[k] || (keys[i+1] && isNaN(keys[i+1]) ? {} : []) : v;
                    }
                } else if (params[k]) {
                    if (Object.prototype.toString.call(params[k]) === '[object Array]') {
                        params[k].push(v);
                    } else {
                        params[k] = [params[k], v];
                    }
                } else {
                    params[k] = v;
                }
            }
        }
        
        return params;
    };
    
})(jQuery);

usage-example.js

var obj = $.deparam('a=1&b[]=2&b[]=3&c=sujeet+abc&arc=true');