RxJS composition operator (Angular environment)

a merge operator

Mix values ​​from multiple Observables into one Observable

import { Component, OnInit } from '@angular/core';
import { of } from 'rxjs/observable/of';
import { range } from 'rxjs/observable/range';
import { merge } from 'rxjs/observable/merge';
import { Observable } from 'rxjs/Observable';

@Component({
  selector: 'app-combine',
  templateUrl: './combine.component.html',
  styleUrls: ['./combine.component.css']
})
export class CombineComponent implements OnInit {

  constructor() { }

  by OnInit () {
    const low: Observable<number> = range(100, 3);
    const middle: Observable<number> = range(200, 3);
    const high: Observable<number> = range(300, 3);
    merge(low, middle, high).subscribe((val: number) => {
      console.log(val);
    });
  }

}