This is possible with useState
or useReducer
, since useState
uses useReducer
internally:
const [, updateState] = React.useState();
const forceUpdate = React.useCallback(() => updateState({}), []);
forceUpdate
isn’t intended to be used under normal circumstances, only in testing or other outstanding cases. This situation may be addressed in a more conventional way.
setCount
is an example of improperly used forceUpdate
, setState
is asynchronous for performance reasons and shouldn’t be forced to be synchronous just because state updates weren’t performed correctly. If a state relies on previously set state, this should be done with updater function,
If you need to set the state based on the previous state, read about the updater argument below.
<…>
Both state and props received by the updater function are guaranteed
to be up-to-date. The output of the updater is shallowly merged with
state.
setCount
may not be an illustrative example because its purpose is unclear but this is the case for updater function:
setCount(){
this.setState(({count}) => ({ count: count + 1 }));
this.setState(({count2}) => ({ count2: count + 1 }));
this.setState(({count}) => ({ count2: count + 1 }));
}
This is translated 1:1 to hooks, with the exception that functions that are used as callbacks should better be memoized:
const [state, setState] = useState({ count: 0, count2: 100 });
const setCount = useCallback(() => {
setState(({count}) => ({ count: count + 1 }));
setState(({count2}) => ({ count2: count + 1 }));
setState(({count}) => ({ count2: count + 1 }));
}, []);