title: Allowing backspaces and numbers and slashes on key press
body: <p>I have this keypress function that only allow numbers and "/" i want to add to it the backspace.
  Does anyone have an idea?</p>
  
  <pre><code>function OnKeyPressNumberText(sender, eventArgs)
  {         
      var char = eventArgs.get_keyCharacter();
      //will allow just letters and "-" 
      var exp = /[^0-9/]/g;
      if (exp.test(char)) {
          eventArgs.set_cancel(true);
      }            
  }
  </code></pre>