How to upload java-script file dynamical

Question

<script>

var oHead = document.getElementsByTagName('HEAD').item(0);

var oScript = document.createElement("script");

var oHead = document.getElementsByTagName('head').item(0);

var lang = 'ca';

var file = 'js/languages/jquery.validationEngine-' + lang + '.js';

oScript.type = "text/javascript";

oScript.src ='{{ URL::asset('/') }}' + file;

alert(oScript.src);

oHead.appendChild(oScript);

</script>

Whats wrong in this. I am getting correct path in alert(oScript.src);