React.

Component model, hooks, rendering, and React ecosystem. Covers 13 sub-skills.

• React · 1 of 3

  Performance (memo, useMemo, useCallback)

  useCallback is used to cache which kind of thing?

  AA promiseBA CSS classCA DOM nodeDA function

• React · 2 of 3

  Refs & DOM Access

  What does mutating ref.current cause?

  AA batched re-render at the end of the current event handlerBA dev warning: React flags the direct DOM mutationCNo re-render: refs are plain containers React ignoresDA synchronous re-render immediately after mutation

• React · 3 of 3

  Core Hooks (useState, useEffect)

  What is the execution order of useInsertionEffect, useLayoutEffect, and useEffect?

  AThe three of them fire at the very same momentBuseInsertionEffect, then useLayoutEffect, then useEffectCuseEffect first, then useLayoutEffect, then useInsertionEffectDOrder depends on the dependency arrays supplied