React JS React is an open-source JavaScript library for building user interfaces or UI components. It was created at Facebook and open-sourced in March of 2013. It is used on social platforms like Instagram, Facebook, Twitter. And It is used on content delivery platforms like NetFlix, Spotify. Beyond Web applications, you can create native mobile applications using React Native. Check your system node and npm version. Node version should be greater than 8.10 and for npm, we need version 5.6. Create a new React-app: Command to create a new react app: npx create-react-app new-app To start the react app: npm start Folder Structure: package.json – It contains all the project dependencies. src folder – It contains the files required to build the application public folder – when we ready to build the app for production all the built files will be placed in the public folder. Create a React element: Elements are the building blocks of React apps
Create an Observable using RxJS: Import the Observable import { Observable } from 'rxjs' ; The Observable execution deliver three types of values: "Next" - sends a value such as a Number, a String, an Object, etc. "Error - sends the Error or exception. "Complete" - does not send a value after the Complete ngOnInit (): void { this . observable$ = new Observable ( subscriber => { subscriber . next ( 1 ); subscriber . next ( 2 ); subscriber . next ( 3 ); subscriber . complete (); //Complete the subscribing here subscriber . next ( 4 ); // Value not send after complete }); this . observable$ . subscribe ( value => { console . log ( value );