What is the difference between useEffect and useLayoutEffect?

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## Understanding the Difference Between useEffect and useLayoutEffect

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### React.js Junior/Middle/Senior

#### useEffect

The `useEffect` hook runs after React has rendered the component and the browser has already painted the changes on the screen, which is why this hook does not block the UI painting. From a lifecycle perspective, `useEffect` is similar to `componentDidMount`, which also runs only after the component is mounted in the DOM and fully available.

##### Typical Use Cases

1. API requests to fetch data;
2. Subscriptions (event listeners, WebSocket);

#### useLayoutEffect

The `useLayoutEffect` hook runs after React has updated the DOM but before the browser paints the page. Because of this, it blocks the UI painting until the code inside the hook has executed. This hook is used when you need to work synchronously with the DOM. In simple terms, `useLayoutEffect` is needed when you need to fix something in the DOM so that the user does not see it.

##### Typical Use Cases

1. Measuring the width or height of elements;
2. Changing scroll position;
3. Synchronously changing styles;
4. Avoiding flickering or jumping of the interface (most common case);

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