RxJS: Improve Your Web Applications With Reactive Programming

  • Thu, Feb 16, 2023
  • 4-minute read

Preface

Today’s Web applications are getting more complex and need to handle more asynchronous events and data flows. However, the processing of these asynchronous events and data streams requires writing a lot of asynchronous code, which often leads to a large amount of code and is difficult to maintain. RxJS provides a reactive programming paradigm that better manages asynchronous events and data flow and helps developers write cleaner, maintainable code.

RxJS basics

RxJS concepts

RxJS is a library based on Observables and Observers.It allows developers to use functional programming to handle asynchronous events and data streams. The main idea behind RxJS is to treat asynchronous events and data streams as an observable sequence that developers can process using operators and subscriptions. RxJS provides a variety of operators to work with this sequence, including create, transform, filter, merge, schedule, and more.

Advantages of RxJS

RxJS offers several advantages:

  • More readable: The functional programming approach used in RxJS makes the code easier to read and understand. Since operators in RxJS can be chained together, developers can more clearly express how data flow should be processed.

  • More flexibility: RxJS provides a variety of operators and combinations. Developers can choose which ones to use and how to combine them depending on the specific use case. This flexibility makes it easier for developers to write high-quality, maintainable code.

  • More efficient: Operators in RxJS make it easier for developers to work with data streams, thus reducing a lot of boilerplate code. The scheduler in RxJS gives you more control over the timing and order of data flow, which can improve the performance of your application.

RxJS in practice

Create Observables

In RxJS, Observables is used to represent an asynchronous event or data stream. Observables can be created in various ways, for example by using operators such as of、from、interval、timer , and so on.

import { of, from, interval } from 'rxjs'; 
// Created using the `of` operator
Observable const observable1 = of(1, 2, 3); 
// Create Observable using the `from` operator
const observable2 = from([1, 2, 3]);
// Created using the `interval` operator
Observable const observable3 = interval(1000);

Subscribe Observables

In RxJS, subscribing to Observables is a way to get access to asynchronous events and data streams. You can subscribe to Observables using the `subscribe`` method and handle asynchronous events and data flows in callback functions.

import { of } from 'rxjs';

const observable = of(1, 2, 3);
observable.subscribe({ 
    next: (value) => console.log(value),
    error: (err) => console.error(err),
    complete: () => console.log('complete'),
    });

In the above example, the next function handles values in Observables, the error function handles errors, and the complete function indicates that Observables are complete.

How to use operators

In RxJS, Observables can be handled with operators, such as filtering, converting, merging, and so on. Here are some common operators:

  • map：Map each Observable value to a new value.
  • filter：Filters Observable values that do not match conditions.
  • tap：Each Observable value is processed without changing the value.
  • merge：Merge multiple Observables into one Observable.
  • switchMap：Converts the Observable to a new Observable.

import { from } from 'rxjs';
import { filter, map, merge, switchMap, tap } from 'rxjs/operators';

const observable1 = from([1, 2, 3, 4, 5]);

observable1
  .pipe(
    filter((value) => value % 2 === 0),
    map((value) => value * 2),
    tap((value) => console.log(value)),
    merge(from([6, 7, 8])),
    switchMap((value) => from([value, value + 1]))
  )
  .subscribe((value) => console.log(value));

In the above example, the filter operator filters the Observable values that do not match the condition, the map operator maps each Observable value to a new value, and the tap operator processes each Observable value. The merge operator merges multiple Observables into one Observable, and the switchMap operator transforms the Observable into a new Observable. Finally, subscribe to Observable using the subscribe method.

Summary

RxJS provides a powerful reactive programming paradigm to better manage asynchronous events and data flows. The use of RxJS enables developers to write cleaner, maintainable code and improve application performance. In this paper, we deeply discuss the concept, principle and practical application of RxJS. Hopefully, this knowledge will help you get a better grasp of RxJS and use it to improve your Web applications in actual development.