title: Why is backspace allowed in my jQuery whether I filter it out or not?
body: <p>I've got this jQuery:</p>
  
  <pre><code>$(document).on("keypress", '[id*=Float]', function (e) { 
      //only allow 1..9 (48..57), '.' (46), and backspace (8)
      var k = e.which;
      if (k === 8 || k === 46) return;
      if (k &lt; 48 || k &gt; 57) { e.preventDefault(); }
  });
  </code></pre>
  
  <p>...working on this HTML:</p>
  
  <pre><code>&lt;input type="text" id="txtbxFloat"&gt;
  &lt;/br&gt;
  &lt;input type="text" id="txtbxHopeFloats"&gt;
  &lt;/br&gt;
  &lt;input type="text" id="txtbxFloatingFreeAsABird"&gt;
  </code></pre>
  
  <p>It can be fiddled with <a href="http://jsfiddle.net/clayshannon/jy6t5oru/22/" rel="nofollow">here</a></p>
  
  <p>It does what the comments say/what I want. However, so does this:</p>
  
  <pre><code>$(document).on("keypress", '[id*=Float]', function (e) { 
      //only allow 1..9 (48..57), '.' (46), and backspace (8)
      var k = e.which;
      if (k === 46) return;
      if (k &lt; 48 || k &gt; 57) { e.preventDefault(); }
  });
  </code></pre>
  
  <p>IOW, the "8" (backspace) is allowed in either case. Why? I guess it's not a problem for me at the moment, but what if I really <em>wanted</em> to prevent a backspace?</p>