merge

signature: merge(input: Observable): Observable

Turn multiple observables into a single observable.


:bulb: This operator can be used as either a static or instance method!

:bulb: If order not throughput is a primary concern, try concat instead!


Examples

Example 1: merging multiple observables, static method

( jsBin | jsFiddle )

import { mapTo } from 'rxjs/operators';
import { interval } from 'rxjs/observable/interval';
import { merge } from 'rxjs/observable/merge';

//emit every 2.5 seconds
const first = interval(2500);
//emit every 2 seconds
const second = interval(2000);
//emit every 1.5 seconds
const third = interval(1500);
//emit every 1 second
const fourth = interval(1000);

//emit outputs from one observable
const example = merge(
  first.pipe(mapTo('FIRST!')),
  second.pipe(mapTo('SECOND!')),
  third.pipe(mapTo('THIRD')),
  fourth.pipe(mapTo('FOURTH'))
);
//output: "FOURTH", "THIRD", "SECOND!", "FOURTH", "FIRST!", "THIRD", "FOURTH"
const subscribe = example.subscribe(val => console.log(val));
Example 2: merge 2 observables, instance method

( jsBin | jsFiddle )

import { merge } from 'rxjs/operators';
import { interval } from 'rxjs/observable/interval';

//emit every 2.5 seconds
const first = interval(2500);
//emit every 1 second
const second = interval(1000);
//used as instance method
const example = first.pipe(merge(second));
//output: 0,1,0,2....
const subscribe = example.subscribe(val => console.log(val));

Additional Resources


:file_folder: Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/patching/operator/merge.ts

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