<pre class="shiki github-dark shaku"><code>class NodeStore { constructor() { this.store = {}; this.id = 1; } /** * @param {Node} node * @param {any} value */ set(node, value) { const id = node.dataset.storeid || this.id++; this.store[id] = value; node.dataset.storeid = id; } /** * @param {Node} node * @return {any} */ get(node) { const { storeid } = node.dataset; return this.store[storeid]; } /** * @param {Node} node * @return {Boolean} */ has(node) { const { storeid } = node.dataset; return storeid in this.store; }}</code></pre>

One more solution, with dataset