ComponentWill

ComponentWill is a JavaScript hook used in React applications to perform specific actions before a component unmounts or when it is removed from the React tree. The ComponentWill method is called when a component is about to be removed from the tree and was a part of the render pipeline in React's earlier versions.

In the update to React 17 and beyond, the ComponentWill method has been removed from React.js, and developers are encouraged to use the useEffect hook instead, which provides similar functionality with more explicit and predictable behavior. However, for older versions of React, ComponentWill still plays a crucial role.

The ComponentWill method accepts two parameters - componentWill: a function to be called before unmounting the component. This was used primarily for older versions of React to update state and other dynamic properties in a lifecycle method that would change at the time of rendition of component(getDerivedStateFromProps ofarakter, you get the value).

React developers should avoid using ComponentWill as much as possible for new components when moving to React 16.3 and higher. However, if working with old components or older codebases, ComponentWill should be used with caution, avoiding explicitly didMount to obtain that Render pipeline.

On deprecation, React advises against direct use of ComponentWill, and instead suggest using usefuleffect or componentDidUpdate methods for updating and combining state. With the transition to a cleaner code practice where component lifecycle can be obtained separately, avoiding ComponentWill, but the approach is slightly different and conducive for good coding practices, instead of trying to trace integration in lifecycle callbacks.