<pre class="shiki github-dark shaku"><code>/** * @param {HTMLElement} tree * @return {string[]} */function getTags(tree) { // your code here let ans = new Set() let treeWalker = document.createTreeWalker(tree, NodeFilter.SHOW_ELEMENT) let currentNode = treeWalker.currentNode while(currentNode) { let tag = currentNode.tagName.toLowerCase() ans.add(tag) currentNode = treeWalker.nextNode() } return [...ans.values()]}</code></pre>

This is my answer.

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.…