What are WeakMap and WeakSet?

Short answer: They are collections that hold weak references to objects — allowing garbage collection if no other reference exists. Example: let obj = {}; let wm = new WeakMap(); wm.set(obj, "value"); obj = null; // entry removed automatically

Example code

They are collections that hold weak references to objects — allowing garbage collection if no other reference exists. Example: let obj = {};
let wm = new WeakMap(); wm.set(obj, "value"); obj = null; // entry removed automatically

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.