什么是 observable、observer 和 subscribe ? [英] What is observable, observer and subscribe in angular?

问题描述

我正在学习 angular，但我对这些 observable、observer 和 subscribe 感到困惑事物.所以请解释一下.

I am learning angular and i got confuse in these observable, observer and subscribe thing. So please explain.

推荐答案

这是一个简单的视觉效果，可以看出区别:

Here is a simple visual to see the difference:

如上所示......Observable 是一个事件或数据流.它们通常从 Angular 方法返回，例如 http.get 和 myinputBox.valueChanges.

As seen above ... an Observable is a stream of events or data. They are often returned from Angular methods, such as the http.get and the myinputBox.valueChanges.

订阅启动"可观察流.如果没有订阅(或异步管道)，流将不会开始发出值.这类似于订阅报纸或杂志……除非您订阅，否则您不会开始获得它们.

Subscribing "kicks off" the observable stream. Without a subscribe (or an async pipe) the stream won't start emitting values. It's similar to subscribing to a newspaper or magazine ... you won't start getting them until you subscribe.

subscribe 方法接收一个观察者.观察者有三种方法:

The subscribe method takes in an observer. An observer has three methods:

• 每次从 observable 发出项目时处理的方法.

• The method to process each time an item is emitted from the observable.

处理发生的任何错误的方法.

The method to process any error that occurs.

观察者完成时清理任何东西的方法.最后一个在处理 Angular 的可观察对象时很少使用.

The method to clean up anything when the observer completes. This last one is seldom used when working with Angular's observables.

希望这会有所帮助.

(而且我同意......试图通过文档的树木看到森林是一个相当大的挑战.我知道他们正在努力改进它们.)

(And I agree ... trying to see the forest through the trees of the docs is quite a challenge. I understand they are working to improve them.)

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