/React-Concept

React-Concept

Introduction to React.js:

Understanding what React.js is, its purpose, and its advantages.

JSX:

Learning about JSX (JavaScript XML), which is a syntax extension for JavaScript used with React to describe what the UI should look like.

Components:

Understanding the concept of components in React, how to create them, and how they can be composed together to build complex UIs.

Props:

Learning about props (short for properties), which are used to pass data from parent to child components.

State:

Understanding state in React, how to manage and update component state, and the difference between props and state.

Lifecycle Methods:

Learning about component lifecycle methods such as componentDidMount, componentDidUpdate, and componentWillUnmount, and how they can be used to perform actions at different points in a component's lifecycle.

Handling Events: Learning how to handle events in React, such as onClick and onChange events.

Forms: Understanding how to work with forms in React, including controlled components and form validation.

React Router:

Learning how to implement routing in a React application using React Router, allowing for navigation between different views or pages.

Hooks:

Learning about hooks, introduced in React 16.8, which allow you to use state and other React features without writing a class component.

Context API:

Understanding the Context API in React, which provides a way to pass data through the component tree without having to pass props down manually at every level.

Redux (optional):

Learning about Redux, a predictable state container for JavaScript apps, which can be used with React to manage the state of your application in a more centralized and predictable way.

Testing:

Understanding how to write tests for React components using tools like Jest and Enzyme.

Best Practices and Patterns:

Learning about best practices and common patterns used in React development, such as container/presentational component pattern, higher-order components, and render props.

React Hooks (useEffect, useState, etc.):

Deep dive into various React hooks and their use cases for managing state, side effects, and more.

Performance Optimization:

Understanding techniques for optimizing the performance of React applications, such as memoization, code splitting, and virtualization.

AXIOS :

Use axios to Fetch, Post data from backend....

INTERVIEW QUESTION OF REACTJS

(1)Explain the Virtual DOM, and a pragmatic overview of how React renders it to the DOM.

What are the limitations of React?

The few limitations of React are as given below:

  • React is not a full-blown framework as it is only a library.
  • The components of React are numerous and will take time to fully grasp the benefits of all.
  • It might be difficult for beginner programmers to understand React.
  • Coding might become complex as it will make use of inline templating and JSX.

What is a Hook?

Hooks allow us to "hook" into React features such as state and lifecycle methods.

React Memo

Using memo will cause React to skip rendering a component if its props have not changed.

This can improve performance

useRef

useRef is a React Hook that lets you reference a value that’s not needed for rendering.

const ref = useRef(initialValue)

Referencing values with refs

When you want a component to “remember” some information, but you don’t want that information to trigger new renders, you can use a ref: const ref = useRef(0);

Example:

Here is an example of a Hook. Don't worry if it doesn't make sense. We will go into more detail in the next section.

***import React, { useState } from "react"; import ReactDOM from "react-dom/client";

function FavoriteColor() { const [color, setColor] = useState("red");

return ( <>

My favorite color is {color}!

<button type="button" onClick={() => setColor("blue")} >Blue <button type="button" onClick={() => setColor("red")} >Red <button type="button" onClick={() => setColor("pink")} >Pink <button type="button" onClick={() => setColor("green")} >Green </> ); }***

const root = ReactDOM.createRoot(document.getElementById('root')); root.render();

You must import Hooks from react.

Here we are using the useState Hook to keep track of the application state.

State generally refers to application data or properties that need to be tracked.

Hook Rules

There are 3 rules for hooks:

-Hooks can only be called inside React function components. -Hooks can only be called at the top level of a component. -Hooks cannot be conditional Note: Hooks will not work in React class components.

Custom Hooks

If you have stateful logic that needs to be reused in several components, you can build your own custom Hooks.