<pre class="shiki github-dark shaku"><code>const detectType = (value) =&gt; { if (value == null) return `${value}`; return (Object.getPrototypeOf(value)?.constructor.name ?? 'object').toLowerCase();}/** * @param {any} data * @return {string} */function stringify(data, cache = new WeakSet()) { const type = detectType(data); if(Number.isNaN(data)) return null; switch (type) { case 'null': case 'number': case 'boolean': case 'undefined': return `${data}`; case 'bigint': throw new Error('[Circular]'); case 'string': return `"${data}"`; case 'date': return `"${data.toISOString()}"`; case 'regex': return data.toString(); case 'symbol': return undefined; case 'Infinity': return 'null' case 'map': case 'object': { if (cache.has(data)) { throw new Error('[Circular]') } cache.add(data); const entries = Array.from(type === 'map' ? [...Object.entries(data), ...data.entries()] : Object.entries(data)); const content = entries.filter(([, value]) =&gt; value !== undefined).map(([key, value]) =&gt; { return `"${key}":${stringify(value, cache)}` }).join(','); return `{${content}}`; } case 'array': case 'set': { if (cache.has(data)) { throw new Error('[Circular]') } cache.add(data); const content = Array.from(data).map((val) =&gt; { if ([null, undefined, Infinity, NaN].includes(val) || (detectType(val) === 'symbol')) { val = null } return stringify(val, cache) }).join(','); return `[${content}]`; } default: return undefined }}</code></pre>

O(N)

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…