title: How to get a variable from my Chrome Extension's background script?
body: <p>I'm making a Google Chrome extension with using this code from Chrome API:</p>
  
  <pre><code>chrome.tabs.executeScript(null,{file : 'inject.js'},function(){})
  </code></pre>
  
  <p>Now I want to get the value from file <code>inject.js</code> to use in my callback function but I don't know how to do that. Can anybody help me?</p>