PHP » UTM парсинг

Получаем значение GET-параметра (аналогичная функция на javascript):

function getParam($paramName) {
    if (isset($_GET[$paramName])) {
        return $_GET[$paramName];
    }
    else {
        return "";
    }
}

echo "utm_source: " . getParam("utm_source");
echo "utm_medium: " . getParam("utm_medium");
echo "utm_term: " . getParam("utm_term");
echo "utm_content: " . getParam("utm_content");
echo "utm_campaign: " . getParam("utm_campaign");