title: Getting viewport height using ExtJS-4X or javascript
body: <p>I want to get the height of the viewport using ExtJs or native javascript.</p>
  
  <p>How can i get this height ? I am not using any extjs viewport container.</p>
  
  <p>If its not possible using ExtJs then how can i find the exact height of the view port ?</p>
  
  <p>Thanks!!</p>