Question

I wish to pass a request parameter to the JavaScript that is to be loaded. This parameter can then be used as a constant within the script.

One example of this is how fancybox 2.x requres a v=2.1.0 parameter as defined in the instructions.

Searching through the fancybox source I could not identify how this gets used, it’s required for both the CSS and JavaScript.

My main requirement for this is to be able to pass in an application context path to the JS which handles ReST requests.

<script type="text/javascript"
        src="<c:url value="/js/rest.js?ctx=${pageContext.request['contextPath']}"/>"></script>

Answer 1

First you have to identify the script (you can give a script tag an id). Scripts are in the document.scripts nodelist. Then you take the src attribute of it (a string), split it on the question mark and take the second element of the resulting array. That can be processed further.

Something like:

var script = document.scripts[0]
   ,params = script.src.split('?')[1].split('&')
   ,paramsObj = {};

for (var i=0;i<params.length;i+=1){
  var keyvalue = params[i].split('=');
  paramsObj[keyvalue[0]] = keyvalue[1];
}