title: Chrome extension, javascript: Tab giving me an error
body: <p>This is my most simple function:</p>
  
  <pre><code>function do_the_redirect(where_to)
  {
  
                  up2 = new Object();
                  up2.url =where_to;
                  //alert("here");
                  chrome.tabs.update(tab.id, up2);
  
  }
  </code></pre>
  
  <p>But it gives me this error:  </p>
  
  <pre><code>Uncaught ReferenceError: tab is not defined
  </code></pre>