<pre class="shiki github-dark shaku"><code>/** * @param {any} data * @return {string} */function stringify(data) { if (typeof data === "bigint") throw "error: bigint not allowed"; if (typeof data === "object") { if (data === null) { return String(null); } else if (data instanceof Array) { const res = data.map((ob) =&gt; { if (typeof ob === "symbol") { return stringify(null); } return stringify(ob); }); return `[${res.join(",")}]`; } else if (data instanceof Date) { return `"${data.toISOString()}"`; } else { const res = Object.keys(data) .filter((k) =&gt; { const enumerable = Object.getOwnPropertyDescriptor( data, k ).enumerable; return data[k] !== undefined &amp;&amp; enumerable; }) .map((k) =&gt; `"${k}":${stringify(data[k])}`); return `{${res.join(",")}}`; } } else if (typeof data === "string") { return `"${data}"`; } else if (typeof data === "number") { if (isFinite(data)) return String(data); return String(null); } else if (typeof data === "boolean") { return String(data); } else if (typeof data === "function" || typeof data === "symbol") { return undefined; } else { return String(null); }}</code></pre>

Recursion : space O(n+d) , Time O(n*d), n -> total elements (Array +obj keys), d -> depth of recursion

I believe you've used JSON.stringify() before, do you know the details of how it handles arbitrary data? Please have a guess on the details and then t…