At the core of the HTTPClient module is the HttpClient. It performs HTTP requests using XMLHttpRequest as the default backend (JSONP is also available, as we will see later in this chapter). It supports requests such as GET, POST, PUT, and DELETE. In this chapter, we will use the HttpClient to make all of these types of requests. As we will see, the HttpClient makes it easy to make these calls with a minimal amount of setup and complexity. None of this terminology will come as a surprise to anyone who has previously worked with Angular or built JavaScript applications that communicate with a backend data store.
However, there is a substantial change in the way Angular handles HTTP requests. Calling a request now returns an Observable of HTTP responses. It does so by using the RxJS library, which is a well-known open source implementation of the asynchronous Observable pattern.
Note
You can find the RxJS project on GitHub at https://github.com/Reactive-Extensions...