title: Delete text in input field not working
body: <p>I have a plus/minus button where you can plug in only numerical values in the input field or click the plus/minus button to select a value. When you go click inside the text field and try to delete or backspace the number it is not working. Here is the html and a link to my fiddle. Update: The delete key works in Chrome but not in Firefox. <a href="https://jsfiddle.net/714dxayk/5/" rel="nofollow">https://jsfiddle.net/714dxayk/5/</a></p>
  
  <pre><code>&lt;span class="form-title"&gt;Quantity&lt;/span&gt;
  &lt;form id='myform' method='POST' action='#' class="numbo"&gt;
  &lt;input type='button' value='-' class='qtyminus' field='quantity' style="font-weight: bold; font-size:18px;" /&gt;
  &lt;input type='text' name='quantity' value='1' class='qty' style="margin-bottom: 0px !important" onkeypress='return event.charCode &gt;= 48 &amp;&amp; event.charCode &lt;= 57'/&gt;
  &lt;input type='button' value='+' class='qtyplus' field='quantity' style="font-weight: bold; font-size:18px;" /&gt;
  &lt;/form&gt;
  </code></pre>