javascript observable
javascript observable
Angular 9 Tutorial | EP16 | rxjs npm (KINDLY SUBSCRIBE)
Complete Playlist: • Angular 9 Tutorial
Part 2: • javascript observable - 2
In this session we will be seeing
Observables in Angular:
way to handle asynchronous programming
ReactX -- asynchronous Programming
Not part of Javascript
Rxjs
Rxjava
Rxpython
Observable
1) Stream of data
2)Observer pattern
2) subscriber subscribed to the Observables can receive data
till the Observables says it is complete or error.
Observables in Angular:
1)EventEmitter @Output
3)Routing - Observables
4)HttpService
complete
Unsubsribing
Creating your own Observable in angular:
import { Component, OnDestroy, OnInit } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import 'rxjs/Rx';
import { Observer } from 'rxjs/Observer';
import { Subscription } from 'rxjs/Subscription';
@Component({
selector: 'app-home',
templateUrl: './home.component.html',
styleUrls: ['./home.component.css']
})
export class HomeComponent implements OnInit, OnDestroy {
numbersObsSubscription: Subscription;
customObsSubscription: Subscription;
constructor() { }
ngOnInit() {
const myNumbers = Observable.interval(1000)
.map(
(data: number) = {
return data * 2;
}
);
this.numbersObsSubscription = myNumbers.subscribe(
(number: number) = {
console.log(number);
}
);
const myObservable = Observable.create((observer: Observer) = {
setTimeout(() = {
observer.next('first package');
}, 2000);
setTimeout(() = {
observer.next('second package');
}, 4000);
setTimeout(() = {
// observer.error('this does not work');
observer.complete();
}, 5000);
setTimeout(() = {
observer.next('third package');
}, 6000);
});
this.customObsSubscription = myObservable.subscribe(
(data: string) = { console.log(data); },
(error: string) = { console.log(error); },
() = { console.log('completed'); }
);
}
ngOnDestroy() {
this.numbersObsSubscription.unsubscribe();
this.customObsSubscription.unsubscribe();
}
}
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