/*
 * Simple isset method for this does not exist in javascript
 */
var isset = function(obj)
{
    return typeof obj !== 'undefined' && obj !== null;
};

//get url params by name
$.urlParam = function (name) {
    var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(window.location.href);
    return results[1] || 0;
};

/* update url string */
function updateQueryString(key, value, urlString) {
    if (!urlString) urlString = window.location.href;

    if (urlString.indexOf(key + '=') > -1) {
        $current = $.urlParam(key);
        if ($current == 0) {
            $split = urlString.split(key + '=');
            $url = $split[0] + key + "=" + value + $split[1];
        }
        else {
            $url = urlString.replace(key + "=" + $current, key + "=" + value);
        }
    } else {
        if (urlString.indexOf('?') == -1) {
            $split = urlString.split('?');
            $url = $split[0] + '?' + key + '=' + value;
        }
        else {
            $url = urlString + '&' + key + '=' + value;
        }
    }
    return $url;
}