Angular and observable objects

If you look at the browser, you will find that the Collector page is empty and there are a bunch of errors in the console. That is because we are trying to work with Observable objects without including the related library into our project. In our Angular 2 seed project, there is a place for vendor packages:

src/vendor.browser.ts

Open this file and simply uncomment the line that imports the RxJS library:

// src/vendor.browser.ts 
// ... 
// RxJS 5 
import 'rxjs/Rx'; 
//... 

Now we can investigate how Observable objects work here. Checking the http object, the task of the get() method is obvious. It is a simple HTTP GET request and returns a response. But what about those map() functions? Where do they come from and what do they do? To answer that question, hold the Ctrl key (or command key if you are using Mac) in your IDE and click on the Http object inside the collector.service.ts. This will take you directly to the definition of the get() method inside the...