What are pure functions?

Short answer: Functions that: Return the same output for the same input. Have no side effects. Example: function add(a, b) { return a + b; // pure }

Example code

Functions that: Return the same output for the same input. Have no side effects. Example: function add(a, b) { return a + b; // pure
}

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.