title: Get InnerWidth of a Div Using Prototype JS
body: <p>I am trying to fetch inner width of a div using Prototype JS which has <code>1px</code> border. In this regard I am using  <code>var wrapper_width = $('wrapper_div').getWidth();</code> </p>
  
  <p>But this method returns whole width including the border width.</p>
  
  <p>How can I fetch inner width of the div excluding the border width ??</p>