title: Firefox console ReferenceError: browser is not defined
body: <p>I am trying to learn WebExtension development for Firefox.  I find the window debugging tools EXTREMELY useful as I can interactively evaluate javascript code in the window context.</p>
  
  <p>For the Webextension APIs at the browser level, I have been totally unsuccessful when trying to similarly use the browser console.  For example trying to use the tabs API</p>
  
  <p>Click on menu->developer->browser console</p>
  
  <p>In the console command line enter any expression beginning with browser and I get </p>
  
  <blockquote>
    <p>"ReferenceError: browser not defined"</p>
  </blockquote>
  
  <p>I have tried in chrome and got same error (read article about chrome.* vs browser.*)</p>
  
  <p>For example trying to find all tabs:</p>
  
  <pre><code>var querying=browser.tabs.query(queryInfo)
  </code></pre>
  
  <p>or</p>
  
  <pre><code>chrome.tabs.query()
  </code></pre>
  
  <p>Returns browser or chrome as not defined</p>
  
  <p>Please help</p>