Posts

Understanding the useEffect Hook

 React is primarily used for building user interfaces, where components re-render based on changes in state or props. But real-world applications often need to interact with external systems—fetching data, subscribing to events, updating the DOM, or starting timers. These are known as side effects, and React’s useEffect hook is the tool designed to handle them in functional components. What is useEffect? The useEffect hook lets you perform side effects in your component. It's React’s way of combining several lifecycle methods from class components (like componentDidMount, componentDidUpdate, and componentWillUnmount) into a single, unified API. Syntax : useEffect(() => {   // side effect code   return () => {     // cleanup code (optional)   }; }, [dependencies]); The first argument is a function containing your side effect logic. The optional second argument is a dependency array that controls when the effect runs. jsx Basic Example import React, { u...

Understanding the useEffect Hook

 React’s component-based approach focuses on rendering UI based on data and state. However, applications often need to perform side effects—like fetching data, setting up subscriptions, or directly manipulating the DOM. That’s where the useEffect hook comes in. Introduced in React 16.8, the useEffect hook allows functional components to perform side effects, a feature previously exclusive to class component lifecycle methods like componentDidMount, componentDidUpdate, and componentWillUnmount. What is useEffect? useEffect is a React Hook that runs after every render by default. It can be used for tasks like: Fetching data from APIs Setting up event listeners Updating the DOM Managing timers or intervals Syntax: useEffect(() => {   // side-effect logic   return () => {     // optional cleanup   }; }, [dependencies]); Basic Example import React, { useState, useEffect } from 'react'; function Timer() {   const [count, setCount] = useState(0);  ...

Managing State with useState Hook

 In React, state is a way to store and manage dynamic data within a component. Before React Hooks, managing state was only possible in class components. But with the introduction of the useState hook in React 16.8, developers can now handle state in functional components, making code cleaner and easier to understand. What is useState? useState is a React Hook that allows you to add state variables in functional components. It takes an initial value as an argument and returns an array containing the current state and a function to update it. Syntax : javascript const [state, setState] = useState(initialValue); Basic Example jsx import React, { useState } from 'react'; function Counter() {   const [count, setCount] = useState(0);   return (     <div>       <h2>Count: {count}</h2>       <button onClick={() => setCount(count + 1)}>Increment</button>     </div>   ); } Here: count is t...

Managing State with useState Hook

 React is known for its component-based architecture, and managing data within those components is made easy with the useState hook. Introduced in React 16.8, useState allows functional components to store and manage local state, eliminating the need to use class components for simple stateful logic. What is useState? The useState hook is a function that lets you add state to functional components. It returns an array with two elements: The current state value. A function to update that state. Basic syntax: const [state, setState] = useState(initialValue); Simple Example import React, { useState } from "react"; function Counter() {   const [count, setCount] = useState(0);   return (     <div>       <h2>Count: {count}</h2>       <button onClick={() => setCount(count + 1)}>Increment</button>     </div>   ); } Here: count holds the current value (starting from 0). setCount updates t...

Props in React: Passing Data Between Components

 In React, components are the building blocks of user interfaces. But how do components talk to each other or share data? The answer lies in props. Short for “properties,” props are a core concept in React used to pass data from one component to another, usually from parent to child. What Are Props? Props are read-only objects that allow you to send data into a component. They work similarly to arguments passed to a function. A parent component can pass any type of data to a child component using props — including strings, numbers, arrays, objects, functions, or even other components. Here’s a basic example: function Greeting(props) {   return <h1>Hello, {props.name}!</h1>; } function App() {   return <Greeting name="Alice" />; } In this case, the App component passes the name prop to the Greeting component, which renders: “Hello, Alice!” Props Are Read-Only One of the fundamental rules in React is that props cannot be changed by the receiving component....

Functional Components vs Class Components

 React, a popular JavaScript library for building user interfaces, allows developers to create components in two main ways: Functional Components and Class Components. Both approaches have their use cases, but with the evolution of React (especially after Hooks), the gap between them has significantly narrowed. Let’s explore the differences, advantages, and best use cases for each. What Are Class Components? Class components are ES6 classes that extend React.Component. They include lifecycle methods and maintain their own state. Example: class Welcome extends React.Component {   constructor(props) {     super(props);     this.state = { name: "User" };   }   render() {     return <h1>Hello, {this.state.name}!</h1>;   } } Class components offer full access to React features, including: Lifecycle methods (componentDidMount, componentDidUpdate) State management this.props and this.state What Are Functional Components? Functi...

Exception Handling in Spring Boot Applications

Exception handling is a crucial part of any web application. In Spring Boot, a robust exception handling mechanism ensures that your application responds gracefully to errors, improving user experience and debugging efficiency. With built-in support and customizable tools, Spring Boot makes exception handling both simple and powerful. Why Exception Handling Matters In a typical application, exceptions like NullPointerException, EntityNotFoundException, or MethodArgumentNotValidException can occur. Without proper handling, these can expose sensitive stack traces or return confusing messages to clients. Instead, a clean and consistent error response format should be used. Default Exception Handling Spring Boot automatically handles many common exceptions and returns appropriate HTTP status codes. For example: @Valid or @Validated failures return 400 Bad Request Missing resources return 404 Not Found However, you often need custom logic, especially for business exceptions or validation er...