React Js Intro


  • Built by facebook in 2013
  • By far the most popular among Angular,Vue, Svelte
  • Its all about components. Indpendent chunks of user interface.
  • Components are reusable.
  • Uses Virtual DOM 
    • Virtual views in memory –> Generate HTML using Javascript
    • No HTML template language
    • Tree reconcilation
  • Be good at Javascript, everything will be easy


  • Install node.js – node js is cross platform Javascript runtime environment which allows us to build fast scalable network applications. 
  • Install the stable version.
  • Check the node version. 
    • node –v


  • Virtual DOM 
  • Just Javascript
  • Battle tested
  • Declarative language
    • We describe user interfaces with React and tell it what we want, and not how to do it. React will take care of the how and translate our declarative descriptions , which we write in react language to actual user interfaces in the browser.
  • Frameworks- disadvantages
    • Do things in a certain way
    • hard to deviate
    • Framework is large and full of features – hard to customize


  • This is JSX
    • return <div>Arrow function !!</div>;
  • Use this below link and play around. 
    • Playground is using a special compiler called Babel – to convert JSX into React API calls.
    • return React.createElement(“div”, null, “Arrow Function!!!”);
      • First is the element to be created
      • Second is the attribute name – here we dont have any attribute so null
      • Child of div elements , here its only string “Arrow Function!!!”
					import React from "react";
import ReactDOM from "react-dom/client";
import "./index.css";

const App = () => {
  return <div>Arrow function !!</div>;

const root = ReactDOM.createRoot(document.getElementById("root"));
    <App />

					import React from "react";
import ReactDOM from "react-dom/client";
import "./index.css";

const App = () => {
  return React.createElement("div", null, "Arrow Function!!!");

const root = ReactDOM.createRoot(document.getElementById("root"));
    <App />



  • Auto Rename tag
  • indent-rainbow 
  • Highlight Matching Tag
  • Prettier
    • format on save
    • format on paste
    • Default formatter dropdown (Prettier – code formatter)
  • Install the extension ES7 Snippets in visual studio code
    • racfe – arrow function with export
    • rfce – regular function
  • Install React Dev tool extension – this is for browser extension not vscode extension.
  • h3#myId.myclass —> <h3 id=”myId” className=”myclass”></h3>
    • Go to  File > Preferences > Settings
    • “emmet.includeLanguages”: {
          “javascript”: “javascriptreact”

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