What does this syntax mean: ? event.charCode : event.keyCode;
<p>I am quite new to JavaScript, and so am still coming into small things that I don't quite understand and don't seem to appear when I search for them.
Please could somebody point me out what the ? : syntax is doing below.</p>

<pre><code>var chCode = ('charCode' in event) ? event.charCode : event.keyCode;
</code></pre>
