title: How to get objectstore from indexedDB?
body: <p>I have indexedDb on my app for web storage.</p>
  
  <p>I would like to get the store form the below code.</p>
  
  <pre><code>var store = myapp.indexedDB.db.transaction(['tree_nodes'],'readwrite').objectStore('tree_nodes'); 
  </code></pre>
  
  <p>It returns error. I was well known of opening indexeddb database and version changing.</p>
  
  <p>The error is <code>Uncaught TypeError: Cannot call method 'transaction' of null</code></p>
  
  <p>I was tried it with the break point. In that case it works fine without errors.</p>
  
  <p>How can i get the store? please help me.</p>
  
  <p>Thanks in advance!</p>