useState Hook

Introduction

The useState Hook is one of the most commonly used Hooks in React. It allows you to add state to functional components. By using useState, you can declare state variables within your functional component and update them as data changes.

Basic Syntax

useState is invoked with the initial state value and returns an array with two elements: the current state variable and a function to update this variable.

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Example Description

In this example:

• useState(0) declares a new state variable count and initializes it to 0.
• setCount is the function that updates the state of count. Each time the user clicks the button, setCount increments count by 1.

Types of Values for State

useState can handle different types of values:

• Numbers: useState(0)
• Strings: useState('Hello')
• Booleans: useState(true)
• Objects: useState({ key: 'value' })
• Arrays: useState([1, 2, 3])

Using Functions to Update State

You can also pass a function to setState that receives the current state as an argument and returns the new state. This is useful when the new state depends on the previous state.

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In this example, prevCount is the previous state, and setCount(prevCount => prevCount + 1) uses that value to compute the new state.

Limitations

It is important to note that useState does not merge the state when it updates. If the state is an object, you must ensure to keep the properties that you are not updating.

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[Placeholder for image about the useState workflow: Diagram showing the data flow when using the useState Hook, including state declaration, state update, and component re-rendering.]