chapter_2.2.md

2.2 useEffect

• useEffect
  • A state depending on a changing state
  • Dependency array
    • No array - executes on each re-render
    • Empty - only on initial render and on last unmount
    • Values - dependencies that trigger useEffect
    • useMemo/useCallback for referential integrity (explain === for objects)
• Unidirectional data flow

![[assets/data_binding.png|150]]