<pre class="shiki github-dark shaku"><code>/** * Approach: * -------- * Use 2 arrays (well 1 array would suffice) to store keys and values separately * Inject the array index (INDEX_KEY) into DOM which is the index its stored at * * set =&gt; add `INDEX_KEY` to the node. * =&gt; push node into key array &amp; value into val array. * =&gt; O[1] * * get =&gt; get the index from the `INDEX_KEY` attribute on DOM node * =&gt; fetch the value from value array based on the index * =&gt; O[1] * * has =&gt; get the index from the `INDEX_KEY` attribute on DOM node * =&gt; check if it exists * =&gt; O[1] * * Space: O[n] =&gt; use of array to store values * * */ class NodeStore { static INDEX_KEY = '__idx'; constructor() { this.nodeKeys = []; // not needed really, can do with just one array this.nodeVals = []; } /** * @param {Node} node * @param {any} value */ set(node, value) { node[NodeStore.INDEX_KEY] = this.nodeVals.length; this.nodeKeys.push(node); // can be removed, not needed. this.nodeVals.push(value); } /** * @param {Node} node * @return {any} */ get(node) { if(NodeStore.INDEX_KEY in node) { return this.nodeVals[node[NodeStore.INDEX_KEY]] } return null; } /** * @param {Node} node * @return {Boolean} */ has(node) { return NodeStore.INDEX_KEY in node; }}</code></pre>

Dom Store using array and indices (Time: O[1], Space: O[n])