Implement reduce

HardHigher Order FunctionsCustom ImplementationsPRO

Rebuild JavaScript reduce as a custom helper with an explicit initial value and callback metadata. This hard exercise focuses on how the accumulator moves through each item, including empty arrays and object summaries.

What you'll practice

Rebuild JavaScript reduce as a custom helper with an explicit initial value and callback metadata
How the accumulator moves through each item
Empty arrays and object summaries

Unlock full access

Choose a plan and go straight to secure checkout.

All 600+ interactive exercises
Full course curriculum
Access to guided projects
All future content included

Secure checkout with Stripe. Cancel anytime.