title: Prevent keyDown event when shift key pressed
body: <p>Please consider this <a href="http://jsfiddle.net/vashzmb5/" rel="nofollow noreferrer">Fiddle</a>.</p>
  
  <p>I want to filter inputs on my input that user can just enter numbers. It works when I pressed alphabet keys and <code>shift</code>+alphabet keys(nothing added to input). But it doesn't work when <code>shift+1 (!)</code> and <code>shift+2(@)</code> and ... .
  Where is my mistake and how can I solve this problem?</p>