How to work with lifting event handlers?

Lifting event handlers or lifting state up is a fundamental design pattern in the React library. The main idea of this approach is that the handler function and the state itself are moved to the nearest common ancestor of those components that need access to this data or need to modify it. This allows synchronizing information between multiple independent child elements through a single source of truth.

The practical implementation of this pattern looks as follows. At the parent component level, a state modification function is created, which is then passed to the child element as a prop, for example, onAction. Inside the child element, props.onAction(data) is called in response to user actions, such as a mouse click or text input.

This approach significantly simplifies both automated and manual component testing. Since the data management logic is extracted into pure functions or isolated handlers, the developer can easily verify their performance without needing to render complex visual trees.

Nevertheless, when actively using this pattern, it is important to avoid redundantly passing too many callbacks through a chain of components. If a child element needs to be passed numerous disjointed functions, it is recommended to combine them into logical action groups or reconsider the interface architecture.

To implement complex interaction scenarios where event handling affects many interrelated parameters, it is better to use the useReducer hook instead of a standard set of callbacks. It allows encapsulating data modification logic into predictable functions and making the code more readable and scalable.