Source Code:

https://stackblitz.com/edit/rt-rxjs-subject-examples

import { from, Subject, AsyncSubject, ReplaySubject, BehaviorSubject, interval } from 'rxjs';

import { map, take, switchMap } from 'rxjs/operators';

console.clear()

const log = console.log;

// The death of a Subject

log('Subject');

log('======='); 

const messageService = new Subject();

// s1 get no data on subscribe. 

messageService.subscribe(x => console.log(x));

messageService.next("Add to Cart");   

messageService.next("Update Item Quantity");   

messageService.subscribe(x => console.log('dynamic subscriber',x));

messageService.next("Checkout"); 

messageService.complete();

 // silently ignored

messageService.next("Checkout"); 

messageService.unsubscribe();

messageService.next("Payment"); 

/*

Source code: https://stackblitz.com/edit/rt-rxjs-subject-examples

import { from, Subject, AsyncSubject, ReplaySubject, BehaviorSubject, interval } from 'rxjs';

import { map, take, switchMap } from 'rxjs/operators';

console.clear()

const log = console.log;

// The shining of a BehaviorSubject

log('BehaviorSubject');

log('================');

const messageService = new BehaviorSubject("Start");

messageService.subscribe(x => console.log(x));

messageService.next("Add to Cart");

messageService.next("Update Item Quantity");

messageService.subscribe(m => console.log(`Dynamic component loaded & received message: ${m}`));

messageService.complete();

log('After complete fetching the latest value:', messageService.getValue());

// silently ignored

messageService.next("Checkout");

messageService.unsubscribe();

// throw error

messageService.next("Payment");

Source Code: https://stackblitz.com/edit/rt-rxjs-subject-examples

import { from, Subject, AsyncSubject, ReplaySubject, BehaviorSubject, interval } from 'rxjs';

import { map, take, switchMap } from 'rxjs/operators';

console.clear()

const log = console.log;

// The shining of a ReplaySubject

log('ReplaySubject');

log('================');

const messageService = new ReplaySubject<string>();

messageService.subscribe(x => console.log(x));

messageService.next("Add to Cart");

messageService.next("Update Item Quantity");

messageService.subscribe(m => log(`#Dynamic component loaded & received message: ${m}`), (e) => { log('error', e) }, () => { });  

messageService.complete();

messageService.subscribe(m => log(`#Dynamic component loaded & received message: ${m}`));

// silently ignored

messageService.next("Checkout");

messageService.unsubscribe();

messageService.next("Payment");

Source Code: https://stackblitz.com/edit/rt-rxjs-subject-examples

import { from, Subject, AsyncSubject, ReplaySubject, BehaviorSubject, interval } from 'rxjs';

import { map, take, switchMap } from 'rxjs/operators';

console.clear()

const log = console.log;

// The shining of a AsyncSubject

log('AsyncSubject');

log('================');

const messageService = new AsyncSubject();

messageService.subscribe(x => console.log('s1',x));

messageService.next("search");

messageService.next("Add to Cart");

messageService.next("Update Item Quantity"); 

messageService.subscribe(m => console.log(`dynamic component loaded & received message: ${m}`));

messageService.complete();

messageService.subscribe(m => console.log(`dynamic component loaded & received message: ${m}`));

// silently ignored

messageService.next("Checkout");

messageService.unsubscribe();

messageService.next("Payment");