ou to not do it. So don&#39;t do it!</p>
<pre><code class="language-javascript">// AVOID
m(&quot;div&quot;, [
    m(&quot;div&quot;, &quot;a&quot;),
    m(&quot;div&quot;, {key: 1}, &quot;b&quot;),
])</code></pre>
<p>If using keys, use a unique key for every element.</p>
<pre><code class="language-javascript">// PREFER
m(&quot;div&quot;, [
    m(&quot;div&quot;, {key: 0}, &quot;a&quot;),
    m(&quot;div&quot;, {key: 1}, &quot;b&quot;),
])</code></pre>
<p>If you need to mix them, create a nested array.</p>
<