主体和行为主体有什么区别? [英] What is the difference between Subject and BehaviorSubject?

问题描述

我不清楚 Subject 和 BehaviorSubject 之间的区别.仅仅是BehaviorSubject 有getValue() 函数吗?

I'm not clear on the difference between a Subject and a BehaviorSubject. Is it just that a BehaviorSubject has the getValue() function?

推荐答案

一个 BehaviorSubject 包含一个值.当它被订阅时，它会立即发出值.主题不包含值.

A BehaviorSubject holds one value. When it is subscribed it emits the value immediately. A Subject doesn't hold a value.

主题示例(使用 RxJS 5 API):

Subject example (with RxJS 5 API):

const subject = new Rx.Subject();
subject.next(1);
subject.subscribe(x => console.log(x));

控制台输出将为空

行为主题示例:

const subject = new Rx.BehaviorSubject(0);
subject.next(1);
subject.subscribe(x => console.log(x));

控制台输出:1

另外:

• BehaviorSubject 应使用初始值创建: new Rx.BehaviorSubject(1)
• 考虑 ReplaySubject 如果您希望主题包含多个值

• BehaviorSubject should be created with an initial value: new Rx.BehaviorSubject(1)
• Consider ReplaySubject if you want the subject to hold more than one value

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