Get querystring value

getQueryString.js

var getQueryString = function(name) {
    var pairs = window.location.search.substring(1).split("&"), pair;
    for ( var i = 0; i < pairs.length; i++) {
        pair = pairs[i].split("=");
        if (pair[0] == name) return pair[1];
    }
    return null;
};