The Ionic CLI
And, give special importance to concepts like Modules, Annotations, Observables, Promises, Dependency Injection etc. when learning typescript.
Don’t worry too much though if these look daunting as I said, with some time and actual practice, all the concepts will sink in. Start with creating the sample ionic projects even if you don’t understand them yet. Try to learn the CLI tool. Then slowly and steadily, you’ll be up and running with ionic!
What you don’t need to learn (rather should avoid): Any version lesser than Ionic 2 and Angular 2.
A Bird’s Eye View might help you too, just an attempt of mine All the best!