How can you polyfill a feature in JavaScript?

Short answer: A polyfill is a piece of code that adds a feature missing in older browsers. Follow me on LinkedIn:

Example code

if (!Array.prototype.includes) { Array.prototype.includes = function(item) { return this.indexOf(item) !== -1; }; }

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.