e JavaScript enhancements.</p>

<p>Feature detection, cutting the mustard, whatever you want to call it, is a fairly straightforward technique. Let’s say you want to traverse the <abbr>DOM</abbr> using <code>querySelector</code> and attach events to some nodes in the document using <code>addEventListener</code>. Your mustard‐cutting logic might look something like this:</p>

<pre><code>if (document.querySelector &amp;&amp; window.addEventListener) {
    // Enhance!
}</code></pre>

<p>There are two poi