title: Validate Multiple Email Addresses with HTML5
body: <p>I'm trying to construct an email form that takes multiple comma separated emails as an input and verifies them using HTML5.  I want to use the following regex to sanity check the input:</p>
  
  <pre><code>\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}\b
  </code></pre>
  
  <p>Here's what I've tried</p>
  
  <p>This doesn't seem to work for more than one:</p>
  
  <pre><code>&lt;input type="email" pattern="\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}\b" value="" multiple&gt;
  </code></pre>
  
  <p>This works, but only does the built in email validation, which seems to be something like <code>.+@.+</code>.</p>
  
  <pre><code>&lt;input type="email" value="" multiple&gt;
  </code></pre>
  
  <p>Is there a way to mix pattern and multiple so the regex checks each item in the comma separated list?</p>
  
  <p>I have a demo here: <a href="http://codepen.io/ben336/pen/ihjKA" rel="noreferrer">http://codepen.io/ben336/pen/ihjKA</a></p>