title: Is there an Android built-in browser developer guide? Where to look for JS engine differences?
body: <p>as I am getting more and more into Android PhoneGap app development, I can see more and more  nuances and little details between built-in Android browsers throughout the versions. I searched for some official or fan document, which would deal with these browser version differences. But I can't find anything useful. </p>
  
  <p>It's a lot frustrating, because you have to test everything on all versions of Android emulator and if app grows big, it's A LOT of work to test all the features in all versions. </p>
  
  <p>Everyone is excited about HTML5, I was too, but only to the point when I moved to doing the real thing. I realized that there is so many problems when dealing with different versions of Android behaving sometimes a lot differently.</p>
  
  <p>If anyone has some good resource to share, I would be very happy. Thanks</p>
  
  <p><strong>EDIT</strong>: Added example of different behaviour betweeen Android browser versions ( but there is many of them):</p>
  
  <p>This works in Android browser in 1.6, 2.2, 2.3 and 2.3.3. But it failes (application crashes or stops JS execution) in Android 2.1:</p>
  
  <pre><code>Object.keys(var).length 
  </code></pre>