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Nov 25, 2019 · /* Here is the magic. The `initialState` pass to * `useReducer` as second argument will be hook * here to init the real `initialState` as return * of this function */ const countInitializer = initialState => { return { count: initialState, otherProp: 0 }; }; const countReducer = state => state; // Dummy reducer const App = => { const [countState /*, countDispatch */] = React.useReducer(countReducer, 2, countInitializer); // Note the `countState` will be initialized state direct on first ...
React docs. useReducer is usually preferable to useState when you have complex state logic that involves multiple sub-values or when the next state depends on the previous one. useReducer also lets you optimize performance for components that trigger deep updates because you can pass dispatch down instead of callbacks.
Option 1: using a Hook useState for each field. This method has the disadvantage of low scalability and some of my real states have at least 15 fields, is unmanageable. Option 2: Using a single setState for the entire object. person: null, pet: null, loading: false.
Nov 5, 2018 · Then write a custom useMiddlewareReducer Hook, which you can see here as useReducer bundled with additional middlewares, akin to Redux applyMiddleware: const [state, dispatch] = useMiddlewareReducer(middlewares, reducer, initState); Middlewares are passed as first argument, otherwise API is the same as useReducer.
Jul 31, 2019 · state = reducers[i](state, action) return state; } Use this as. // At module level, so the combined function doesn't change. const combinedReducer = combineReducers(reducer1, reducer2); // Inside your component. const [state, dispatch] = useReducer(combinedReducer, initialState) Edit: I have recently taken a like for reduce function and I think ...
Dec 10, 2019 · In order to test that your BarComponent updates when the reducer updates, you'll need a way to trigger dispatch from within the component, since you're calling useReducer inside your component. Here's an example: export function BarComponent() {. const [state, dispatch] = useReducer(FooReducer, []);
Feb 7, 2019 · useReducer's state is local to a single component - if you wanted to use this state throughout your app, you'd need to pass it (and/or the dispatch function) down via the props. It's effectively just a more structured version of useState - in fact, useState is implemented using useReducer under the hood !
Feb 12, 2019 · The way I compared both approaches was as follows: const [state, updateState] = useState(); const [reducerState, dispatch] = useReducer(myReducerFunction); I passed each of them once to a context object, which was being consumed in a deeper child (I just ran separate tests, replacing the value by the function that I wanted to test ...
Dec 20, 2019 · 32. If you want to pass the state and the dispatch through context you have to type it on the context, you can go with just this line but if you want type safety read further. { team: null }, () => {}, You can change the <any> inside React.Dispatch to your action types if you want type safety for actions, you would also need to type the action ...
Let's say we have userReducer defined like this: function userReducer(state: string, action: UserAction): string { switch (action.type) { case "LOGIN": return action.username; case "
