我不太清楚 Subject 和 BehaviorSubject 之间的区别。行为主体是否只有 getValue 功能?
一个 BehaviorSubject 保存一个值。当它被订阅时,会立即发出该值。主题不持有值。
主题示例(使用 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
行为主体示例:
const subject = new Rx.BehaviorSubject();
subject.next(1);
subject.subscribe(x => console.log(x));
控制台输出:1
此外:
**行为主题将在订阅时返回初始值或当前值***
var subject = new Rx.BehaviorSubject(0); // 0 is the initial value
subject.subscribe({
next: (v) => console.log('observerA: ' + v) // output initial value, then new values on `next` triggers
});
subject.next(1); // output new value 1 for 'observer A'
subject.next(2); // output new value 2 for 'observer A', current value 2 for 'Observer B' on subscription
subject.subscribe({
next: (v) => console.log('observerB: ' + v) // output current value 2, then new values on `next` triggers
});
subject.next(3);
有输出:
observerA: 0
observerA: 1
observerA: 2
observerB: 2
observerA: 3
observerB: 3
**主题不会在订阅时返回当前值。它只在调用.next(value)
时触发,并返回/输出value
***。
var subject = new Rx.Subject();
subject.next(1); //Subjects will not output this value
subject.subscribe({
next: (v) => console.log('observerA: ' + v)
});
subject.subscribe({
next: (v) => console.log('observerB: ' + v)
});
subject.next(2);
subject.next(3);
控制台输出如下:
observerA: 2
observerB: 2
observerA: 3
observerB: 3
我刚刚了一个项目,解释所有科目之间的**区别:<br/>; https://github.com/piecioshka/rxjs-subject-vs-behavior-vs-replay-vs-async