What is the implementation principle of React hooks?

Hooks in React are special functions used to store state and handle side effects in functional components. The implementation of Hooks can be explained in two aspects: the render phase and the commit phase.

During the render phase, React will execute the function component and collect all the Hooks used in the component. React will determine the return value of each hook based on the order of the Hooks and store them in an internal data structure for use in the component’s lifecycle. When the component is re-rendered, React will re-execute the component function and determine which hooks need to be updated by comparing the order of hook calls in the previous and current render.

During the commit phase, React will update the actual DOM based on the updated state of Hooks. React will compare the dependencies of Hooks between the previous and current renderings, and decide whether to update the component based on the result of the comparison. If the dependencies of Hooks have not changed, React will skip the update. If the dependencies of Hooks have changed, React will re-invoke the function component, get the new return value of Hooks, and update the corresponding state and side effects of the component. Additionally, React will also perform other DOM operations during the commit phase, such as calling the side effect functions defined in the effect hook.

In general, the implementation principle of React Hooks can be summarized as collecting and managing the state of Hooks during the render phase, and updating the DOM and handling side effects based on the updated state of Hooks during the commit phase. This implementation allows functional components to have the ability to have state and side effects, while avoiding common issues in class components such as this binding and the complexity of lifecycle functions.