See if value exists and then get the value
<p>So basicly, when a form is submitted on a comment and in the comment it contains <code>@username</code> or <code>@</code> then someone's username, I want to do something, e.g. send a notification to the username.</p>

<p>So, if it contains an <code>@</code> and a word (with letters or numbers) afterwards, I want to get the value and do something with it.</p>

<p>e.g.</p>

<pre><code>if (contains an @ symbol, get the value of it)  {
// do something
}
</code></pre>
