useState – React

useState는 컴포넌트에 state 변수를 추가할 수 있게 해주는 React 훅입니다.

• Reference
  • useState(initialState)
  • set functions, like setSomething(nextState)
• Usage
  • Adding state to a component
  • Updating state based on the previous state
  • Updating objects and arrays in state
  • Avoiding recreating the initial state
  • Resetting state with a key
  • Storing information from previous renders
• Troubleshooting
  • I’ve updated the state, but logging gives me the old value
  • I’ve updated the state, but the screen doesn’t update
  • I’m getting an error: “Too many re-renders”
  • My initializer or updater function runs twice
  • I’m trying to set state to a function, but it gets called instead

Reference

• convention is to name state variables like [something, setSomething] using array destructuring

Parameters

• initialState
  • The value you want the state to be initially.
  • It can be a value of any type, but there is a special behavior for functions. This argument is ignored after the initial render
• If you pass a function as initialState, it will be treated as an initializer function.

This is development-only behavior and does not affect production.

If your initializer function is pure (as it should be), this should not affect the behavior.