How to check if a querystring key is present via javascript

Following is the JavaScript code to check whether a key is present in querystring or not:

    <script type="text/javascript">
        
        var queryKeyPresent = function(key) {
            var url = window.location.href;
            if (url.indexOf('?' + key + '=') != -1) {
                return true;
            } else if (url.indexOf('&' + key + '=') != -1) {
                return true;
            }
            return false;
        };
        
    </script>

Usage:

        var check = queryKeyPresent('q');
        var check2 = queryKeyPresent('userid');

The above code will look whether the key exists just after the questionmark (?) or present in some successive keys in querystring.