使用 Observable 的 Angular 8 轮询

Question

Hey i am upgrading my Project from angular 5 to angular 8. This is the code i was using for polling.

 Observable.interval(this.intervalTime).timeout(600000)
                .takeWhile(() => this.alive)
                .subscribe(i => {
                    this.timeOutValue++;
                    //fun();
                });

fun() is setting alive as true or false. But now in angular 8 interval is not defined. Will someone please help me for workaround.

Answer 1

Use the interval function from 'rxjs' and perform your operations in a pipe.

import { interval } from 'rxjs';
import { timeout, takeWhile } from 'rxjs/operators';

class MyClass {
  private intervalTime: number;
  private alive: Subject<any> = new Subject<any>();
  private timeOutValue = 0;

  myPollingMethod() {
    interval(this.intervalTime).pipe(
      timeout(600000),
      takeWhile(() => this.alive)
    ).subscribe(i => {
      this.timeOutValue++;
      //fun();
    });
  }
}

Answer 2

Use a throttle time for continuous polling or debounce

Rx.Observable.interval(1000).throttleTime(2000).subscribe(x => console.log())
const interval$ = interval(1000);
const debouncedInterval = interval$.pipe(debounce(val => timer(val * 200)));
const subscribe = debouncedInterval.subscribe(val =>
console.log(`Example Two: ${val}`)
);