title: What javascript fallback does best simulate html5 form validation
body: <p>I have built an app that validates forms client side with html5. I'm looking for the javascript-implementation that best emulates this behavior in older browsers.</p>
  
  <p>Important qualities are:</p>
  
  <ul>
  <li>As similar behavior as possible.</li>
  <li>As little modification of css/html as possible</li>
  <li>As little functionality besides field-validation built in as possible</li>
  </ul>