javascript - Load a particular JS file base on what URL its hosted -

i've mvc asp page following code:

<script type="text/javascript" src="https://test_domain.com/test.js"> </script> @*<script type="text/javascript" src="https://live_domain.com/live.js"> </script>*@ 

essentially comment or uncomment script want use if site live or if on test. i'd love able dynamically how. 1 solution, perhaps, if read current url , figure out if live/test.

updated answer (thanks whipdancer)

in web.config have added url:

<add key="bundlejs" value="https://test_domain.com/test.js" /> <!--<add key="bundlejs" value="https://live_domain.com/live.js" /> 

i web.config transformations next. better had before.

the next step during session_start in global.asax.cs file set url application variable:

application["bundlejs"] = system.configuration.configurationmanager.appsettings["bundlejs"]; 

after set able go controller of view (tip: in case view layout went parent controller). on or after actionresult method added application variable viewbag

viewbag.bundlejs = httpcontext.application["bundlejs"]; 

finally in cshtml page (which _layout me) set script up

   <script type="text/javascript" src="@viewbag.bundlejs"> </script> 

since using asp.net mvc - can use web config transformations handle different environments.

more info on web config transformations

i use web config parameter determine appropriate environment, loaded via global.asax (or possible in primary view controller).

you able automatically determine appropriate url based on environment compiled to.

in test web.config:  <appsettings>     <add key="jssource" value="https://test_domain.com/test.js" /> </appsettings>  in release web.config:  <appsettings>     <add key="jssource" value="https://live_domain.com/live.js" /> </appsettings> 

in global.asax like:

public class mvcapplication : system.web.httpapplication {     public static string jsurl;      protected void application_start()     {         jsurl = system.configuration.configurationmanager.appsettings["jssource"];     } } 

in page use this:

<script type="text/javascript" src="@jsurl"> </script> 

** don't think code run is. give general idea.