RxJS：Multicasting运算符publishReplay

publishReplay利用行为主题，其中，它可以缓冲值并将其重放给新订阅者，并返回ConnectableObservable。connect()方法必须用于订阅创建的可观察对象。

语法

publishReplay(value); // here value is the number of times it has to replay.

例

import { interval} from 'rxjs';
import { take, publishReplay} from 'rxjs/operators';

let observer = interval(1000).pipe(
   take(3),
   publishReplay(2)
);
const subscribe_one = observer.subscribe(
   x => console.log("Value from Sub1 = "+x)
);
const subscribe_two = observer.subscribe(
   x => console.log("Value from Sub2 = "+x)
);
observer.connect();
setTimeout(() => {
   const subscribe_three = observer.subscribe(
      x => console.log("Value from Sub3 = "+x)
   );
}, 2000);

输出