<pre class="shiki github-dark shaku"><code>class NodeStore { static nodeKey = '__nodeStoreKey__'; constructor() { this.values = []; this.length = 0; } /** * @param {Node} node * @param {any} value */ set(node, value) { if (this.has(node)) { this.values[node[NodeStore.nodeKey]] = value; } else { node[NodeStore.nodeKey] = this.length; this.values[this.length] = value; this.length++; } } /** * @param {Node} node * @return {any} */ get(node) { if (this.has(node)) { return this.values[node[NodeStore.nodeKey]]; } } /** * @param {Node} node * @return {Boolean} */ has(node) { return NodeStore.nodeKey in node }}</code></pre>
T: O(1)
S: O(N)

This is my accepted solution