title: Injecting a global variable before page load
body: <p>I've <a href="https://www.irctc.co.in" rel="nofollow noreferrer">this page</a>  and in my background page I'm blocking  a url which defines <code>stationName</code> variable.</p>
  
  <p>As explained in
  <a href="https://stackoverflow.com/questions/9515704/building-a-chrome-extension-inject-code-in-a-page-using-a-content-script/9517879#9517879">Insert code into the page context using a content script</a> I'm able to inject <code>stationName</code> variable( using first technique) but unfortunately it gets injected too late, after execution of all downloaded javascript code from website which don't find <code>stationName</code> variable. </p>
  
  <p>How to define this variable before the javascript execution of page starts?</p>