如何在零时间内获得RxJS Observable事件？ [英] How to get RxJS Observable events in zero time?

问题描述

我正在将一个Observable的所有事件收集到数据数组：

I'm collecting all the events of an Observable to a data array:

const obs$ = Rx.Observable
  .interval(500)
  .take(4);

let data = [];
const start = performance.now();

obs$.subscribe(
  value => {
    data.push({
      time: performance.now() - start,
      data: value
    });
  },
  () => {},
  () => {
    console.log(JSON.stringify(data, null, 2));
  }
);

<script src="https://unpkg.com/rxjs@5.2.0/bundles/Rx.js"></script>

是否有可能预见未来并获得相同的数据数组没有等待2秒？

Is it possible to "foresee the future" and get the same data array without waiting 2 seconds?

为了澄清，我试图找到一种方法以某种方式包装给定的Observable（Ò bs $ 在上面的示例中）带有自定义计时器/调度程序，因此我可以立即获取事件。

To clarify, I'm trying to find a way to wrap somehow a given Observable (obs$ in the example above) with a custom timer/scheduler so I could get the events immediately.

推荐答案

您可以创建 <$ c $的实例c> VirtualTimeScheduler 并且可以在 interval 的调用中指定它。

You can create an instance of the VirtualTimeScheduler and can specify it in the call to interval.

如果您在订阅后在调度程序上调用 flush ，则会立即发出事件：

If you then call flush on the scheduler after subscribing, the events will be emitted immediately:

const scheduler = new Rx.VirtualTimeScheduler();

const obs$ = Rx.Observable
  .interval(500, scheduler)
  .take(4);

let data = [];
const start = scheduler.now();

obs$.subscribe(
  value => {
    data.push({
      time: scheduler.now() - start,
      data: value
    });
  },
  () => {},
  () => {
    console.log(JSON.stringify(data, null, 2));
  }
);

scheduler.flush();

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<script src="https://unpkg.com/rxjs@5.2.0/bundles/Rx.js"></script>

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