Question

使可观察的间隔以延迟时间（以秒为单位）发射整数和每个新值的最佳方法是什么？

interval().subscribe(v => console.log(v))

预期：

1  --- after 1 second
2  --- 2 seconds after 1 was emitted
...
37 --- 37 seconds after 36 was emitted
...

我已经为您创建了沙箱-https://stackblitz.com/edit/rxjs-task-delay?file=index.ts

Answer 1

当我们使用mergeMap时，所有内部可观测对象在创建后立即被订阅，因此我们不会得到越来越大的时间间隔，因为interval每秒发射一次，因此所有内部可观测对象在源发出后立即订阅：

source.pipe(
  mergeMap(num => of(num).pipe(
    delay(num * 1000)
  )
)

emits 1 after 1 sec., inner waits 1 sec 
emits 2 after 1 sec., inner waits 2 sec (1 sec already passed)
emits 3 after 1 sec., inner waits 3 sec (2 secs already passed)

但是在先前完成之前，concatMap内部没有被订阅：

source.pipe(
  concatMap(num => of(num).pipe(
    delay(num * 1000)
  )
)

Sandbox example

Answer 2

我已经完成了BehaviorSubject：

import {  BehaviorSubject} from 'rxjs'; 


const sub = new BehaviorSubject(1);

sub.subscribe( val => {
  console.log( val);
  setTimeout( () => {sub.next(val+1);}, val*1000);
  });

在https://stackblitz.com/edit/rxjs-task-delay-41r4b1上玩

具有基于值的延迟的interval（）

2 个答案: