title: Regex Replace anything but numbers and lowercase
body: <p>I have an input which I am binding to keyup()</p>
  
  <p>On each keyup, I want it to:</p>
  
  <ol>
  <li>disallow any characters that are not a number, a letter, or a dash, and  </li>
  <li>replace any uppercase characters with lowercase ones.</li>
  </ol>
  
  <p>Regex makes my head explode, any help?</p>
  
  <pre><code>$('.my-input').keyup(function() {
      this.value = this.value.replace(/[^0-9a-z-]/g,/[0-9a-z-]/g);
  });
  </code></pre>