throttleTime

signature: throttleTime(duration: number, scheduler: Scheduler): Observable

Emit latest value when specified duration has passed.

Examples

Example 1: Receive latest value every 5 seconds

( jsBin |
jsFiddle )

import { interval } from 'rxjs/observable/interval';
import { throttleTime } 'rxjs/operators';
//emit value every 1 second
const source = interval(1000);
/*
  throttle for five seconds
  last value emitted before throttle ends will be emitted from source
*/
const example = source.pipe(throttleTime(5000));
//output: 0...6...12
const subscribe = example.subscribe(val => console.log(val));

Example 2: Throttle merged observable

( jsBin |
jsFiddle )

import { interval } from 'rxjs/observable/interval';
import { merge } from 'rxjs/observable/merge';
import { throttleTime, ignoreElements } from 'rxjs/operators';
const source = merge(
  //emit every .75 seconds
  interval(750),
  //emit every 1 second
  interval(1000)
);
//throttle in middle of emitted values
const example = source.pipe(throttleTime(1200));
//output: 0...1...4...4...8...7
const subscribe = example.subscribe(val => console.log(val));

Additional Resources

• throttleTime
  - Official docs
• Filtering operator: throttle and throttleTime
  - André Staltz

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