The problem, as poncha pointed out, is that as far as ASP.NET is concerned, the content delivered in your .js file is a string. It does not apply any sort of rendering before IIS delivers it. It gets the same treatment any other content file would, like a .jpg or .png.
In order to call server side methods (like ResolveUrl), you need to use the <% ... %> syntax within any page that is parsed by ASP.NET (like an .aspx or .master file).
By the way, these little code blocks go by a lot of different names:
In particular, we want a Displaying Expression with the syntax <%= ... %>, where:
the value that is entered after the equals sign is written into the current page
Knowing that, we can build our own own URL by using ResolveClientUrl() which:
returns a URL string suitable for use by the client to access resources on the Web server
To this, we‘ll pass in the Web Application Root Operator or ~ character, where ASP.NET:
resolves the ~ operator to the root of the current application:
By combining these, we can save the result of the displaying expression into a javascript variable by placing the following code on your Master Page (adapted from Joel Varty‘s blog):
The following script should place before the external JavaScript reference
<script type="text/javascript">
var baseUrl = ‘<%= Page.ResolveClientUrl("~/") %>‘;
</script>Since JavaScript variables are inherently global, any other script can now access the baseUrl variable, so we can utilize it from the .js file with the following script:
function ResolveUrl(url) {
return url.replace("~/", baseUrl);
}Now you can call ResolveUrl("~/DynamicMenu.ashx") directly from your javascript file and it will create the appropriate URL by stripping out "~/" and replacing it with the baseUrl created earlier by the server side script.
Further Reading: