React State — What are states in React

What Are States?
Why Use State in React?
useState Hook
State Best Practices

State is one of the most important concepts in React that enables dynamic and interactive user interfaces. In this comprehensive guide, we will understand what state is, why we need it, and how to use the useState Hook effectively with practical examples.

What Are States?

State is a special variable that belongs to a component. Unlike Props, which are passed from parent to child, state is managed inside the component itself. When state changes, React re-renders the component automatically to show the updated data.

Consider states as variables within a component that can undergo changes over time and receive updates on the DOM.

Props vs State

Props: Data passed from parent to child. Read-only.
State: Data managed inside a component. Can be updated.

Why Use State in React?

State is essential in React applications for several reasons:

Dynamic UI Updates: State allows components to react to user interactions and update the interface accordingly.
Component Memory: State preserves values between renders, maintaining data throughout the component's lifecycle.
Predictable Updates: React's state management ensures consistent and reliable UI updates.
Performance: React optimizes re-renders by batching state updates.

Remember: Not all component data needs to be state. Use state only for values that might change and affect the component's rendering.

Use the useState Hook

Since Hooks were introduced (React 16.8), use the useState Hook to create and manage state in function components.

Here count is a variable and setCount is a function which triggers a re-render of the component.


// App.jsx
import {useState} from "react";

function Counter() {
  const [count, setCount] = useState(0);

  return (
    <div>
        <h2>You clicked {count} times</h2>
  <button onClick={() => setCount(prev => prev + 1)}>Click Me</button>
    </div>
  );
}

export default Counter;

count is the state variable.
setCount is the function to update the state.
useState(0) sets the initial value of count to 0.

Know more about useState Hook

State Best Practices

Follow these best practices to effectively manage state in your React applications:

Keep State Minimal: Only store values in state that directly affect the UI rendering.
Use Multiple State Variables: Split complex state into smaller, manageable pieces when it makes sense.
Avoid Redundant State: Don't store values that can be computed from existing state or props.
Use Functional Updates: When new state depends on previous state, use the functional update form:
```
setCount(prevCount => prevCount + 1)
```
Initialize State Properly: Use meaningful initial values that prevent unnecessary UI flicker.

💡 Pro Tip: Consider using useReducer for complex state logic or when multiple state updates are related.

Popular hooks in react

useState - for managing state in functional components.
useEffect - for handling side effects in functional components.
useContext - for accessing context in functional components.
useReducer - for managing complex state logic in functional components.
useRef - for accessing DOM elements and persisting values across renders.