URL param parsing as generated by jQuery.param. Supports both "legacy" style (ex. foo=bar&foo=bar2&bar=foo) as well as new style (ex. foo[]=bar&foo[]=bar2&bar[]=foo). Original fork did not support legacy style where the key had multiple values. When wanting to parse the document's url, remember to only pass in the document.location.search or doc…

parseParams.js

(function(factory){
    if (typeof define === "function" && define.amd) {
        // AMD. Request jQuery and then run the plugin
        define(factory );
    } else {
        // Global jQuery
        window.parseParams = factory();
    }
}(function() {

    /**
     * Converts a string that was serialized with jQuery.param back to the object.
     *
     * @param {String} str
     *
     * @return {Object}
     * 
     * @example:
     * 
     *  parseParams('foo=bar&foo=bar2&bar=foo');
     * 
     *  parseParams('foo[]=bar&foo[]=bar2&bar[]=foo');
     * 
     */
    var parseParams = function parseParamsFn(str) {
       
        var obj         = {}, pair,
            pairs       = decodeURIComponent(str).split( "&" ),
            prevkey, key, prev, newobj, newkey, arg,
            injectParam = function(key, val) {
                
                var firstBracket = key.indexOf('[');
    
                if (firstBracket === -1) {
                    
                    if (obj[key] !== undefined) {
                        
                        if (!(obj[key] instanceof Array)) {
                            
                            obj[key] = [ obj[key] ];
                            
                        }
                        
                        obj[key].push(val);
                         
                    } else {
                        
                        obj[key] = val;
                        
                    }
                    
                    return;
                }
    
                prevkey = key.substring(0, firstBracket);
                key     = key.substr(firstBracket);
                prev    = obj;
    
                key.replace(/\[([^\]]+)?\]/g, function(chunk, idx, pos) {
                    var newobj, newkey;
                    if (chunk.match(/\[\d*\]/)) {
                        newobj = prev[prevkey] || [];
                        newkey = idx || '[]';
                    } else {
                        newobj = prev[prevkey] || {};
                        newkey = idx;
                    }
    
                    if (prevkey === '[]') {
                        prev.push(newobj);
                    } else {
                        prev[prevkey] = newobj;
                    }
    
                    prev = newobj;
                    prevkey = newkey;
                });
    
                if (prevkey === '[]') {
                    prev.push(val);
                } else {
                    prev[prevkey] = val;
                }
            };
    
        // If not string was passed in, return an empty object
        if (!str) {
            
            return obj;
            
        }
    
        for( arg = 0; arg < pairs.length; arg++ ) {
            pair = pairs[ arg ].split( "=" );
            injectParam(
                String(pair[0]).replace(/\+/g, " "),
                String(pair[1]).replace(/\+/g, " ")
            );
        }
    
        return obj;
       
    };
    
    return parseParams;

}));