Reducers are functions that take the current state and an action as arguments, and return a new state result. In other words, (state, action) => newState.
Using a State Reducer with Hooks
- End user does an action
- Dev calls dispatch
- Hook determines the necessary changes
- Hook calls dev's code for further changes 👈 this is the inversion of control part
- Hook makes the state changes
given to useEffect after the initial render, you can give it an empty array as second argument.
useEffect(() => {
loadDataOnlyOnce();
}, []);- To update multiple states on top of the previous state, use setState with the
spread operator .... - To update multiple states that will override all values in the state, use setState without the spread operator.
No ,useState is asynchronous
State Hook
A Hook is a special function that lets you “hook into” React features. For example, useState is a Hook that lets you add React state to function components. We'll learn other Hooks later. Component Lifecycle Every React Component has a lifecycle of its own, lifecycle of a component can be defined as the series of methods that are invoked in different stages of the component's existence. ... A React Component can go through four stages of its life as follows.
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