React 18 new Hooks

If you’re a React 18 enthusiast, then you’ve landed on the right page. In this blog, we will discuss the new hooks introduced in React 18. So, let’s dive deeper into React 18 hooks with detailed explanations and examples.

useTransition

The useTransition hook allows you to defer the rendering of components until a certain condition is met, which helps create smooth transitions and animations. It coordinates the timing of component rendering to avoid janky UI updates. Here’s an example:

import { useTransition } from 'react';
function App() {
const [show, setShow] = useState(false);
const handleClick = () => {
setShow(!show);
};
const transitions = useTransition(show, {
enter: { opacity: 1, transform: 'scale(1)' },
leave: { opacity: 0, transform: 'scale(0.5)' },
});
return (
<div>
      <button onClick={handleClick}>Toggle</button>
      {transitions((styles, item) =>
        item ? (
          <div style={styles}>Content</div>
        ) : null
      )}
    </div>
  );
}

In the example above, the transition variable returned by useTransition is a function that takes a callback as an argument. The callback receives styles and item parameters. styles contain the style properties for the component during the transition, and the item represents the current state of the transition (true or false). The transitions function returns the rendered component based on the transition state.

useMutableSource

The useMutableSource hook allows you to integrate external data sources or libraries more efficiently within React’s rendering pipeline. It manages mutable data sources and provides better performance and updates to components. Here’s an example:

import { useMutableSource } from 'react';
function App() {
const mutableSource = getMutableSource(); // Get the mutable source from an external library
const data = useMutableSource(mutableSource, getData, subscribe);
return <div>{data}</div>;
}

In this example, getMutableSource() retrieves the mutable source from an external library. getData is a function that fetches the data from the mutable source, and subscribe is a function that registers a callback for receiving data updates. The useMutableSource hook manages the subscription and updates the data variable when changes occur in the mutable source.

useDeferredValue

The useDeferredValue hook allows you to defer the update of certain values until a later point in time, optimizing the rendering of components. It’s useful for preventing unnecessary renders when dealing with expensive computations or API calls. Here’s an example:

import { useDeferredValue } from 'react';
function App() {
const [searchTerm, setSearchTerm] = useState('');
const deferredSearchTerm = useDeferredValue(searchTerm, { timeoutMs: 500 });
useEffect(() => {
// Perform search API call using deferredSearchTerm
// This API call will be delayed by 500 milliseconds
// if the searchTerm updates within that time period
}, [deferredSearchTerm]);
const handleChange = (event) => {
setSearchTerm(event.target.value);
};
return ;
}

In this example, useDeferredValue is used to create the deferredSearchTerm variable, which represents the deferred value of the searchTerm state. When the searchTerm updates, the API call inside the useEffect hook is delayed by 500 milliseconds using the timeoutMs option. If a new searchTerm value is set within that time period, the API call is further delayed.

useTransitionState

The useTransitionState hook provides a way to track and manage the state of a transition. It helps coordinate state changes during transitions, making it easier to handle animations or complex UI updates that involve multiple steps. Here’s an example:

import { useTransitionState } from 'react';
function App() {
const [show, setShow] = useState(false);
const transitionState = useTransitionState(show);
const handleClick = () => {
setShow(!show);
};
return (
    <div>
      <button onClick={handleClick}>Toggle</button>
      {transitionState === 'entering' && <div>Entering</div>}
      {transitionState === 'entered' && <div>Entered</div>}
      {transitionState === 'exiting' && <div>Exiting</div>}
      {transitionState === 'exited' && <div>Exited</div>}
    </div>
  );
}

In this example, the transitionState variable represents the state of the transition based on the show state. It can have four possible values: ‘entering’, ‘entered’, ‘exiting’, and ‘exited’. Based on the transitionState, different components are rendered to display messages during different stages of the transition.

useSyncExternalStore

The useSyncExternalStore hook enables synchronization between a React component and an external state management system, such as Redux or MobX. It helps bridge the gap between React and external state management solutions, allowing for better integration and interoperability. Here’s an example:

import { useSyncExternalStore } from 'react';
function App() {
const store = getExternalStore(); // Get the external state management store
const [value, setValue] = useSyncExternalStore(store, 'value');
const handleChange = (event) => {
setValue(event.target.value);
};
return ;
}

In this example, getExternalStore() retrieves the external state management store, such as Redux or MobX. The useSyncExternalStore hook synchronizes the value state variable with the ‘value’ key in the external store. When setValue is called, it updates both the React component state and the corresponding value in the external store, ensuring synchronization between the two.

Please note that the examples provided are based on hypothetical hooks that were discussed as potential features in React 18. The actual implementation and behavior of these hooks may differ in the final release. I recommend referring to the official React documentation and release notes for accurate information once React 18 becomes available.