title: regex email explanation
body: <p>I'm new to regex and not sure how each part of the below breaks down to testing for email, especially the <code>!</code> at beginning and the <code>._%+0-</code></p>
  
  <pre><code>!/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i.test(values.email)
  </code></pre>