angular observable code example

Example 1: understanding Observable.create(

import { Observable } from "rxjs/Observable";

var observable = Observable.create(function subscribe(observer) {
    observer.next('Hey guys!')
})

// OR 

var observable = Observable.create((observer:any) => {
    observer.next('Hey guys!')
})

Example 2: observable tutorial angular

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      // Create an Observable that will start listening to geolocation updates
// when a consumer subscribes.
const locations = new Observable((observer) => {
  let watchId: number;

  // Simple geolocation API check provides values to publish
  if ('geolocation' in navigator) {
    watchId = navigator.geolocation.watchPosition((position: Position) => {
      observer.next(position);
    }, (error: PositionError) => {
      observer.error(error);
    });
  } else {
    observer.error('Geolocation not available');
  }

  // When the consumer unsubscribes, clean up data ready for next subscription.
  return {
    unsubscribe() {
      navigator.geolocation.clearWatch(watchId);
    }
  };
});

// Call subscribe() to start listening for updates.
const locationsSubscription = locations.subscribe({
  next(position) {
    console.log('Current Position: ', position);
  },
  error(msg) {
    console.log('Error Getting Location: ', msg);
  }
});

// Stop listening for location after 10 seconds
setTimeout(() => {
  locationsSubscription.unsubscribe();
}, 10000);

Example 3: angular observable pipe exemple

import { Component, OnInit } from '@angular/core';
import { Observable, of} from 'rxjs';
import { map, filter, tap } from 'rxjs/operators'
 
 
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
 
  obs = new Observable((observer) => {
    observer.next(1)
    observer.next(2)
    observer.next(3)
    observer.next(4)
    observer.next(5)
    observer.complete()
  }).pipe(
    filter(data => data > 2),                    //filter Operator
    map((val) => {return val as number * 2}),    //map operator
  )
 
 data = [];
 
  ngOnInit() {
    this.obs1.subscribe(
      val => {
        console.log(this.data)
      }
    )
  }
 
}