Implement deepClone — handle Dates, RegExp, Map, Set & circular refs

Question

Accepted Answer

**Approach:** Recursive clone with `WeakMap` for seen objects. Handle each built-in type, then plain object via `Reflect.ownKeys`.

```javascript
function deepClone(obj, seen = new WeakMap()) {
  if (obj === null || typeof obj !== 'object') return obj;
  if (seen.has(obj)) return seen.get(obj);
  if (obj instanceof Date) return new Date(obj);
  if (obj instanceof RegExp) return new RegExp(obj.source, obj.flags);
  if (obj instanceof Map) {
    const c = new Map(); seen.set(obj, c);
    for (const [k,v] of obj) c.set(deepClone(k, seen), deepClone(v, seen));
    return c;
  }
  if (obj instanceof Set) {
    const c = new Set(); seen.set(obj, c);
    for (const v of obj) c.add(deepClone(v, seen));
    return c;
  }
  if (Array.isArray(obj)) {
    const c = []; seen.set(obj, c);
    obj.forEach((v,i) => c[i] = deepClone(v, seen));
    return c;
  }
  if (obj instanceof ArrayBuffer) return obj.slice(0);
  const c = Object.create(Object.getPrototypeOf(obj));
  seen.set(obj, c);
  for (const

Implement deepClone — handle Dates, RegExp, Map, Set & circular refs

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Understand the problem

Attempt it yourself

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Solution ready — 2 min read

Join the discussion

Discussion (0)

KEEP THESTREAK ALIVE.

KEEP THE
STREAK ALIVE.