title: Injecting custom JS Code using Selenium Web Driver
body: <p>I'm writing automated UI tests in C# using Selenium 2 Web Driver for web application written in ASP.NET and MS AJAX. I would like to "inject" custom JS code on the beginning of test which will execute every time async postback is finished. Example code below</p>
  
  <pre><code>function EndRequestHandler(sender, args)
  {
     DoSomeStuff(...);
  }
  
  Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
  </code></pre>
  
  <p>The question is how to do this using Selenium (I don't want to modify original application). This have to be compatible with IE, Firefox and Chrome drivers, so using custom profiles for Firefox is not an option (although I might be missing something here)</p>