de> in an <code>div</code> in the example above, the key must be moved to the <code>div</code>.</p>
<pre><code class="language-javascript">// AVOID
users.map(function(u) {
    return m(&quot;div&quot;, [ // key should be in `div`
        m(&quot;button&quot;, {key: u.id}, u.name)
    ])
})</code></pre>
<h4 id="avoid-hiding-keys-in-component-root-elements"><a href="#avoid-hiding-keys-in-component-root-elements">Avoid hiding keys in component root elements</a></h4>
<p>If you refactor the code and make a user 