[RxJS] ReplaySubject

最新推荐文章于 2025-05-08 13:45:51 发布

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最新推荐文章于 2025-05-08 13:45:51 发布

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原文链接：http://www.cnblogs.com/Answer1215/p/5784861.html

本文介绍了ReplaySubject在RxJS中的作用及其与普通Subject的区别。ReplaySubject能够缓存其值并重新发送给新订阅者，即使序列未完成也能正常工作。通过示例对比了ReplaySubject与普通Subject的行为差异。

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A ReplaySubject caches its values and re-emits them to any Observer that subscrubes late to it. Unlike with AsyncSubject, the sequence doesn't need to be completed for this to happen.

The normal subject won't emit the value before subscribe.

var subject = new Rx.Subject();

subject.onNext(1);

subject.subscribe(
  (x)=>{
    console.log("Receive the value: " + x);
  }
)

subject.onNext(2);
subject.onNext(3);

/*
"Receive the value: 2"
"Receive the value: 3"
*/

The ReplaySubject will cache the values:

var subject = new Rx.ReplaySubject();

subject.onNext(1);

subject.subscribe(
  (x)=>{
    console.log("Receive the value: " + x);
  }
)

subject.onNext(2);
subject.onNext(3);

/*
"Receive the value: 1"
"Receive the value: 2"
"Receive the value: 3"
*/