Angular 4, Ionic 3, and TypeScript

Many of us coming from the Angular 1 world to Angular 2 or 4 will surely see that it's an entire rewrite of the application and a steep learning curve. I felt the same when I initially started Ionic and Angular, but gradually as I read about the concepts of Angular, many of the problems we used to face in Angular 1 were automatically solved without any effort. Initially you will miss the old controllers, services, filters, and other concepts in Angular 1 and most importantly the navigation and routing. But when you pe deep into the topics you will find that corresponding modules such as component, providers, and pipe are available and that they can be used in similar ways. Navigation and router are also now used as push and pop mechanisms for navigating from one page to another page. In the initial beta versions of Ionic 2, we don't have proper URL-based routing as users can't land on a specific page in the application. But after a stable Angular-router is released it has been added to Ionic 2, which has opened the path for better support for progressive web apps, which will allow the same Ionic apps to be shipped as mobile web applications. Ionic 3 also added support for responsive grids, which will help when we will be building desktop applications. Lazy Loading is another important feature added, which reduces the initial loading time of the application. Still, as Ionic 3 is in initial days, we can expect these features to become a lot more stable. As, we know Ionic 2 and 3 did not have any major framework changes, so initially we will be comparing Angular 1 and 2 in this chapter so it helps users understand the difference and how they can migrate to the latest Ionic versions.