Angular 4.3 introduced a new HttpClient service, which is a replacement for the Http service from Angular 2. It works mostly the same as the old service, handling both single and concurrent data loading with RxJs Observables, and writing data to an API.
Lately, I have worked on a few projects where a single-page Angular app is contained within a site built on a server-side framework like Django. One of the challenges is to get their URLs to play nicely together.
Say you have a project with an Angular 2 front end and an API back end using the Django Rest Framework. Further, imagine that your Angular 2 page is also served from within the Django app. Your URL structure might look like this:
Update, November 27, 2017: This post explains the Http service used in Angular 2. This is now deprecated in favor of the newer HttpClient released in Angular 4.3. This post will remain here as long as Angular 4.x is in long term support. If you are using Angular 5, consider upgrading to the newer HttpClient. You can find a tutorial for the HttpClient service in my post Angular 5: Making API calls with the HttpClient service.
Angular 2 provides a new pattern for running asynchronous requests, called Observables. Here, we will review a few of the concepts and eventually see how to run multiple concurrent HTTP requests, with the callbacks running only after all of them have completed.