Get query string Params from a URL

getParams.js

    var getParams = function (url) {
        // get query string from url (optional) or window
        var queryString = url ? url.split('?')[1] : location.search.slice(1);

        // we'll store the parameters here
        var obj = {};

        // if query string exists
        if (queryString) {

            // stuff after # is not part of query string, so get rid of it
            queryString = queryString.split('#')[0];

            // split our query string into its component parts
            var arr = queryString.split('&');

            for (var i = 0; i < arr.length; i++) {
                // separate the keys and the values
                var a = arr[i].split('=');

                // in case params look like: list[]=thing1&list[]=thing2
                var paramNum = undefined;
                var paramName = a[0].replace(/\[\d*\]/, function (v) {
                    paramNum = v.slice(1, -1);
                    return '';
                });

                // set parameter value (use 'true' if empty)
                var paramValue = typeof (a[1]) === 'undefined' ? true : a[1];

                // (optional) keep case consistent
                paramName = paramName.toLowerCase();
                paramValue = paramValue.toLowerCase();

                // if parameter name already exists
                if (obj[paramName]) {
                    // convert value to array (if still string)
                    if (typeof obj[paramName] === 'string') {
                        obj[paramName] = [obj[paramName]];
                    }
                    // if no array index number specified...
                    if (typeof paramNum === 'undefined') {
                        // put the value on the end of the array
                        obj[paramName].push(paramValue);
                    }
                    // if array index number specified...
                    else {
                        // put the value at that index number
                        obj[paramName][paramNum] = paramValue;
                    }
                }
                // if param name doesn't exist yet, set it
                else {
                    obj[paramName] = paramValue;
                }
            }
        }

        return obj;
    };