What does the `window` mean in RxJS?

Question

I'v heard about the buffer. Seems like the window is similar to the buffer. What's the difference between them? and WHY it's called a 'window'??

Answer 1

Buffer is a specialization of Window.

Window notifies you immediately of new windows, along with an observable to observe the values that will be in that window.

In contrast, Buffer does not notify you immediately of new windows. Instead it internally collects the items in the window. When the window is complete, Buffer will send a notification with an array containing all of the items in the window.

Conceptually, you can write buffer by using window like so:

Rx.Observable.prototype.buffer = function () {
    return this.window
        .apply(this, arguments)
        .flatMap(function (w) { return w.toArray(); });
};

As to why it is called "window"...unless the Rx authors come answer, any answers will be purely speculative. Window is a term commonly used to represent a time interval in many disciplines, including software development & signal processing.