How to add javascripte in larava

How to add javascript in laravel.

Error=>Use of undefined constant s - assumed 's'

<script>
       function run() {

           var a = document.getElementById("save");

           var value = document.getElementById("selectP").value;

           var s = "Referrdetails/"+value;

           a.href = "";

       }

</script>

via Chebli Mohamed