Lesson 03 · 12 min
Lists, keys and effects
An array in JSX is `.map`. A key isn't the index if the list moves. An effect isn't for calculations.
12 minLesson 3 of 8Practice includedAsk AI on any point
A list is drawn like this: items.map((item) => <li key={item.id}>{item.title}</li>). key tells React which row is which when the array shifts. An index as key breaks when inserting into the middle: input fields "move" to other rows.
Sign in to continue
The rest of this lesson opens after sign up
The first lesson of every course is open without an account. To read on, solve the practice and use Ask, create a free account or log in.