What 's the difference between components and custom hooks?

React Components and Custom Hooks are two very important concepts in React. They serve different purposes but both aim to help developers build user interfaces and logic more efficiently.

React Components

React Components are the basic building blocks of React applications, defining the structure and presentation of the application. The core of a component is its render method, which describes the UI layout. By composing multiple components, you can build complex user interfaces. React components can be class components or function components, with function components becoming more powerful and popular after the introduction of Hooks in React 16.8.

Example:

jsx
function Welcome(props) {
  return <h1>Hello, {props.name}!</h1>;
}

This simple function component accepts a props object and returns a JSX element representing a welcome message.

Custom Hooks

Custom Hooks are a mechanism for sharing logic across multiple components without duplicating code. You can extract component logic into reusable functions. Custom Hooks are typically functions whose names start with use, clearly indicating that they adhere to React Hooks rules.

Example:

jsx
function useWindowWidth() {
  const [width, setWidth] = useState(window.innerWidth);

  useEffect(() => {
    const handleResize = () => setWidth(window.innerWidth);
    window.addEventListener('resize', handleResize);
    return () => {
      window.removeEventListener('resize', handleResize);
    };
  });

  return width;
}

This custom Hook useWindowWidth allows any component to easily obtain and respond to changes in window width.

Key Differences

1. Purpose and Application:

   • Components primarily handle the structure and presentation of UI.
   • Custom Hooks are mainly used for abstracting and reusing state logic; they do not render any UI but provide data and behavior to components.

2. Return Values:

   • Components return React elements that form part of the page.
   • Custom Hooks return data or functions for use by one or more components.

3. Use Cases:

   • Use Components when you need to create visual UI elements.
   • Use Custom Hooks when you need to share logic or state across multiple components, such as data fetching, subscriptions, or DOM interactions.

Through these differences and examples, we can see the distinct purposes and strengths of React components and custom Hooks. In actual development, leveraging both appropriately can significantly improve the maintainability and reusability of applications.