<pre class="shiki github-dark shaku"><code>class NodeStore { /** * @param {Node} node * @param {any} value */ constructor() { this.nodes = {}; } set(node, value) { node.__nodeStoreKey__ = Symbol(); this.nodes[node.__nodeStoreKey__] = value; } /** * @param {Node} node * @return {any} */ get(node) { return this.nodes[node.__nodeStoreKey__]; } /** * @param {Node} node * @return {Boolean} */ has(node) { return !!this.nodes[node.__nodeStoreKey__]; }}</code></pre>

This is my accepted solution