Get Query String Using Javascript

Weeks ago I needed to get queystring parameters using JavaScript. I found a function called querySt(), this function is quite useful but I added an extra line that returns the string "undefined" in the case that the requested parameter does not exists in the querystring. My final code is:

function querySt(ji) {

    hu = window.location.search.substring(1);

    gy = hu.split("&");

    for (i = 0; i < gy.length; i++) {

        ft = gy[i].split("=");

        if (ft[0] == ji) {

            return ft[1];

        }

    }

    return "undefined";

}