The testing of the smallest parts of the application through unit testing may seem strange to new developers.
When the applications reach the production level, then the developers start separating the smallest testable parts of an application for the testing (let’s say functions for printing a text on the console), as it assures that new changes in the development mode don’t break the core features
Angular ngFor is a built-in Directive that allows us to iterate over a collection. This collection is typically an array, however can be “array-like”. To demonstrate this, we’ll be using Rx.Observable.of() to initialise our collection with an Observable instead of a static array.
Angular claims to be very fast by default. What does “fast” really mean? Of course, this always depends on the context. What does our application do? How many different things is it doing at a certain point? How is our application’s component tree structured and how many bindings does it introduce? This and other questions come into play when trying to figure out, how we can make our applications faster.