什么是RxJS？

Reactive Extension JavaScript. It's a reactive streams library that allows you to work with asynchronous data streams.
We represent asynchronous data streams using observable sequences.

什么是asynchronous data streams?

1. asynchronous: When we called a function and want to be notified when the result is available,we will have to register a callback. In this way,we can continue with execution without worrying about the webpage becoming unresponsive.

2. data: Raw information in JavaScript.

3. streams: Sequences of data,in other words,information made available over time. Different from arrays,it doesn't have to be present in order.

何谓observable sequences?

就是observables。Observables are flexible and have to patterns: push and pull.

push pattern: We use the push pattern to subscribe to the source stream and react to new data.

pull pattern: We use the pull pattern in the same way above but,synchronously.