Reuse Angular Code within NativeScript Apps

NativeScript is a great framework to write mobile Apps for Android and iOS with Angular (2, 4 and so on).

Read on, if you:

• have an existing Angular Web App or are planning to develop one
• you want to offer a native App for Android and iOS without a lot of extra work

TL;DR It is possible to reuse code, especially Services and Pipes, if you are lucky some of the Components.

I will show three possibilities to share code between a web and a native app, but in regards to usability keep following in mind:

• a website has more static content and more space to show elements
• a smartphone has a smaller screen, users are used to the native elements and want to find/use stuff inside apps fast without much distraction

So maybe it is not the best practice to port a web app 1:1 on a native app.

But now, the three possibilities …

1. Seed Projects

https://github.com/jlooper/angular-starter

Goal:

• a single workspace with a working Angular Web App and NativeScript App
• maximum code reuse, at first only templates are platform dependent
  • Angular: *.html
  • NativeScript: *.tns.html
• shared code in “shared” folder
• own build system

Pro:

• easy to start a project

Contra:

• mobile and web UIs are different, so at a long run, you are going to need components for each platform and can only share services and pipes
• lot’s of build “magic”

2. npm-package

Goal:

• pack your shared code into a npm package
• shared Angular should be placed in Angular modules
• use the package and the modules in your NativeScript app

Pro:

• useful if your web app is already finished
• projects can be placed in different folders

Contra:

• you need a build system and a private npm repository

3. shared-folder

Goal:

• web app client: put all shared angular code into a “shared” folder
• include the “shared” folder via symlinks into your NativeScript app/ folder

Pro:

• nice for prototyping
• pragmatic
• every project can use the own build tool

Contra:

• not sure, if it works under Windows
• Angular versions and other dependencies always have to be the same in both projects

Hints

• don’t reference  window in shared code
• abstract platform specific code with e.g. facade pattern (there is no local-storage on a mobile app)
• use the same npm dependencies

Conclusion

I used the last approach to write a prototype NativeScript app from an existing web-app (Calendar for Trello). I was able to reuse the a complete redux store and all of the services, after I matched the dependencies on both projects.

I didn’t reuse any of the components, because in my opinion the mobile app had a different use case. It worked quite well and showed us, that it’s possible to reuse code and get a native UI with NativeScript.