react hook in javascript

React hooks are functions that allow us to use React state and lifecycle features in functional components. They were introduced in React 16.8 and are a way to simplify React components and eliminate the need for class-based components in many cases.

Here are the basic steps to use React hooks in JavaScript:

1. Import the necessary hooks from React:

index.tsx
import React, { useState, useEffect, useContext } from 'react';
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2. Declare state variables using the useState hook:

index.tsx
const [count, setCount] = useState(0);
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The above code declares a state variable called 'count' and a function called 'setCount' that can be used to update the value of 'count'.

3. Use the useEffect hook to handle side effects:

index.tsx
useEffect(() => {
  document.title = `You clicked ${count} times`;
}, [count]);
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The above code sets the document title based on the value of 'count'. The useEffect hook takes a function as its first parameter and an array of dependencies as its second parameter. The function will be called after every render if any of the dependencies have changed.

4. Use the useContext hook to access context values:

index.tsx
const theme = useContext(ThemeContext);
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The above code uses the useContext hook to access the 'theme' value from the nearest ThemeContext provider.

These are just a few examples of how to use React hooks in JavaScript. There are other hooks available such as useRef, useReducer, and useCallback that can be used for more advanced scenarios.