publish

signature: publish() : ConnectableObservable

Share source and make hot by calling connect.

Ultimate RxJS

Examples

Example 1: Connect observable after subscribers

( StackBlitz | jsBin | jsFiddle )

// RxJS v6+
import { interval } from 'rxjs';
import { publish, tap } from 'rxjs/operators';
//emit value every 1 second
const source = interval(1000);
const example = source.pipe(
//side effects will be executed once
tap(_ => console.log('Do Something!')),
//do nothing until connect() is called
publish()
);
/*
source will not emit values until connect() is called
output: (after 5s)
"Do Something!"
"Subscriber One: 0"
"Subscriber Two: 0"
"Do Something!"
"Subscriber One: 1"
"Subscriber Two: 1"
*/
const subscribe = example.subscribe(val =>
console.log(`Subscriber One: ${val}`)
);
const subscribeTwo = example.subscribe(val =>
console.log(`Subscriber Two: ${val}`)
);
//call connect after 5 seconds, causing source to begin emitting items
setTimeout(() => {
example.connect();
}, 5000);

Additional Resources

📁 Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/publish.ts