<pre class="shiki github-dark shaku"><code>/** * @param {HTMLElement} tree * @return {string[]} */function getTags(tree) { if (!tree || !tree.children) { return []; } const queue = [tree]; const tags = new Set(); while (queue.length &gt; 0) { const currentLevelSize = queue.length; for (let i = 0; i &lt; currentLevelSize; i++) { const currentNode = queue.shift(); if (currentNode?.children) { queue.push(...currentNode.children); } tags.add(currentNode.nodeName.toLowerCase()); } } return [...tags];}</code></pre>

Implement using `Set`

Given a DOM tree, please return all the tag names it has. Your function should return a unique array of tags names in lowercase, order doesn't matter.…