Mid level: Lifecycle Methods and Hooks in React

As a mid-level developer, understanding and effectively using React Hooks and lifecycle methods is crucial for building robust, maintainable, and scalable applications. This article will delve into essential hooks, custom hooks, and advanced hook patterns, such as managing complex state with useReducer and optimizing performance with useMemo and useCallback.

Introduction to React Hooks

React Hooks allow you to use state and other React features without writing a class. Introduced in React 16.8, hooks provide a simpler and more functional approach to state management and lifecycle methods.

Key Benefits of Hooks

1. Simpler Code: Hooks enable you to use state and lifecycle methods directly in functional components, leading to more readable and maintainable code.
2. Reuse Logic: Custom hooks allow you to extract and reuse stateful logic across multiple components.
3. Enhanced Functional Components: Hooks provide all the capabilities of class components, such as managing state and side effects, without needing to use classes.

Essential Hooks

useState

useState is a hook that lets you add state to functional components.

Example:

import React, { useState } from 'react';

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

  return (
    <div>
      <p>You clicked {count} times</p>
      <button onclick="{()"> setCount(count + 1)}>Click me</button>
    </div>
  );
};

export default Counter;

In this example, useState initializes the count state variable to 0. The setCount function updates the state when the button is clicked.

useEffect

useEffect is a hook that lets you perform side effects in functional components, such as fetching data, directly interacting with the DOM, and setting up subscriptions. It combines the functionality of several lifecycle methods in class components (componentDidMount, componentDidUpdate, and componentWillUnmount).

Example:

import React, { useState, useEffect } from 'react';

const DataFetcher = () => {
  const [data, setData] = useState(null);

  useEffect(() => {
    fetch('https://api.example.com/data')
      .then(response => response.json())
      .then(data => setData(data));
  }, []);

  return (
    <div>
      {data ? <pre class="brush:php;toolbar:false">{JSON.stringify(data, null, 2)}

: 'Loading...'}