Reduce() Polyfill From Scratch | Ace Your JavaScript Interview

Learn how the JavaScript reduce() method actually works internally by building your own reduce polyfill from scratch. In this video, we’ll understand: • How Array.reduce() works • What accumulator and currentValue mean • How initial values work in reduce • Why iteration starts from index 1 sometimes • How reduce handles sparse arrays • How to create a custom myReduce() method using Array.prototype This is a very common JavaScript interview question asked in companies like Apple, Amazon and ByteDance. If you’re preparing for JavaScript interviews or want to deeply understand JavaScript internals, this video will help a lot. Subscribe for more JavaScript interview questions, polyfills, React concepts and frontend development content.