![]() ![]() #React redux useselector updateReact-Redux has a shallowEqual function to compare data to determine when to update data. įor example, we can use useSelector as follows: import React from "react" import ReactDOM from "react-dom" import const rootElement = document.getElementById("root") ReactDOM.render(, rootElement ) We can also use the shallowEqual function from React-Redux as the equalityFn argument to useSelector. If we want to retrieve multiple values from the store, we can call useSelector multiple times with each call returning a single field value, use Reselect or a similar library to create a memoized selector that returns multiple values in an object but returns a new object when one of the values is changed. This is different from connect, which uses shallow equality checks on the results of mapState calls to determine if re-rendering is needed. UseSelector only forces a re-render if the selector result appears to be different than the last result. A cached result may be returned if the selector is run and returns the same result. The provided selector function will be called and its result will be returned from the useSelector hook. React update batching behavior will cause multiple useSelector s in the same component to return new value should only return in a single re-render. Each call creates an individual subscription to the Redux store. We may call useSelector multiple times within a single function component. Props can be used through closure or by using the curried selector. The selector function doesn’t receive an ownProps argument. When an action is dispatched, useSelector will do a shallow comparison of the previous selector result value and the current one. The return value of the selector will be used as the return value of the useSelector hook. The selector function may return any value as a result, not just an object. The selector will be called with the entire Redux store state as its only argument. The useSelector hook returns whatever is returned by this selector function. It’s equivalent to mapStateToProps in connect. This selector function receives the redux state as its argument. The call takes the following format: const result : any = useSelector(selector : Function, equalityFn? : Function) The useSelector hook takes a selector function to select data from the store and another function equalityFn to compare them before returning the results and determine when to render if the data from the previous and current state are different. ![]() The hooks API consists of the useSelector, useDispatch, and useStore hooks. ![]() Using the useSelector Hook in a React Redux App In this article, we’ll look at the new hooks React-Redux Hooks API. It can work alone and it’s also a popular state management solution for React apps when combined with React-Redux. With Redux, we can use it to store data in a central location in our JavaScript app. Photo by Clark Street Mercantile on Unsplash ![]()
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