React Hooks were added to React in version 16.8, and they’ve completely changed the way we write React apps. Before hooks, we had to use class components to manage state and lifecycle methods, which could make our code complicated, especially in larger apps. Hooks allow us to use functional components to handle things like state, side effects, and performance optimization more easily.

With hooks, we can:

• Manage state (useState),
• Handle side effects, like fetching data (useEffect), and
• Improve performance (useMemo, useCallback).

In this article, we’ll go through the most important React Hooks that you need to know. I’ll explain what each one does, why it’s useful, and how to use it in your projects to make your React code simpler and more efficient.

1. useState

What It Does:
useState lets you add state to functional components. Before hooks, only class components could have state, but now you can use it in functional components too. This hook returns two things: the current state and a function to update that state.

When to Use It:
Use useState when you need to track a value that changes over time, like user input in a form, or a toggle state for showing and hiding elements.

Example:

Why It’s Important:
It makes handling simple state in functional components easy and keeps your code more readable than class components.

Let’s try and learn: useState Hook in React — Crash Course by Web Dev Simplified

2. useEffect

What It Does:
useEffect lets you run side effects in your components, such as fetching data, updating the DOM, or subscribing to something like a WebSocket. It runs after the component renders, and you can control when it runs by passing dependencies.

When to Use It:
Use useEffect whenever you need to run code after rendering or when a value changes, such as fetching data from an API when the component mounts or updating the document title when a value changes.

Example:

Why It’s Important:
It replaces the old lifecycle methods like componentDidMount and componentDidUpdate, making it easier to handle side effects in a cleaner, declarative way.

Let’s try and learn: React useEffect Hook — What, Why, and How by Web Dev Simplified

3. useContext

What It Does:
useContext allows you to access values from a context without having to pass props manually at every level of your component tree (also called "prop drilling"). It makes it easy to share data like the current theme, user authentication status, or language settings across your app.

When to Use It:
Use useContext when you have data or functions that need to be accessed by multiple components, such as global settings, themes, or shared states.

Example:

Why It’s Important:
It simplifies the process of passing data through many layers of components and keeps your code DRY (Don’t Repeat Yourself).

Let’s try and learn: React useContext Hook Tutorial by Web Dev Simplified

4. useReducer

What It Does:
useReducer is like useState, but better for managing more complex state logic. Instead of just setting state directly, you send actions to a reducer function, which determines how the state should change based on the action.

When to Use It:
Use useReducer when your component’s state management becomes too complex for useState, such as when you need to handle multiple related pieces of state or state transitions.

Example:

Why It’s Important:
It’s ideal for managing states that have many transitions (e.g., form state or state with complex actions). It also makes it easier to understand and predict how state changes.

Let’s try and learn: useReducer Hook — React Hooks Tutorial by Web Dev Simplified

5. useMemo

What It Does:
useMemo helps improve performance by caching the result of a computation and only recomputing it when its dependencies change. It’s particularly useful for expensive calculations or when rendering large lists.

When to Use It:
Use useMemo when you have an expensive calculation (e.g., sorting, filtering) that shouldn’t be recomputed on every render unless certain values (dependencies) have changed.

Example:

Why It’s Important:
It prevents unnecessary recalculations, improving the performance of your app, especially in components that rerender frequently.

Let’s try and learn: React useMemo Hook — Avoid Unnecessary Calculations by Web Dev Simplified

6. useCallback

What It Does:
useCallback is similar to useMemo, but it memoizes a function instead of a value. It ensures that a function reference remains the same between renders, which can prevent unnecessary re-renders in child components that rely on that function.

When to Use It:
Use useCallback when passing a function as a prop to a child component, and you don’t want that child to re-render unnecessarily whenever the parent component re-renders.

Example:

Why It’s Important:
It prevents performance issues by stopping functions from being recreated on every render, which can cause child components to re-render even when not necessary.

Let’s try and learn: React useCallback Hook Tutorial by The Net Ninja

7. useRef

What It Does:
useRef gives you access to a mutable object that persists across renders. It's often used to reference DOM elements directly or to store values that don't trigger a re-render when updated.

When to Use It:
Use useRef when you need to interact with a DOM element directly (e.g., focusing an input) or when you need to store a value that doesn't change the UI (e.g., a timer ID).

Example:

Why It's Important:
It's essential for working with the DOM directly and for managing mutable values without causing unnecessary re-renders.

Let's try and learn: useRef Hook - React Tutorial by Web Dev Simplified

Conclusion:

Mastering these React Hooks will make you a more efficient developer, enabling you to write cleaner, more scalable code. Hooks like useState and useEffect handle basic state and side effects, while more advanced hooks like useMemo, useReducer, and useContext help you optimize performance and manage more complex logic with ease.