Migrating a large Angular 1 application to Angular 2 can be a big undertaking. We recommend the following order of operations during conversion.
Move as much code as possible into pure TypeScript modules
Write framework-agnostic unit tests for that code
Good candidates for this are stateless services
If used, replace the
ng-app directive with
UpgradeAdapter singleton and replace "bootstrap".
Identify components (directives) of the app most likely to benefit from Angular 2
These could be parts of the app where performance is a problem,
parts where there will be more active development or
parts that could really benefit from Angular 2 libraries or components.
Convert all service dependencies from Angular 1 to Angular 2
.factory Angular services to
Leverage TypeScript classes
upgradeAdapter.downgradeNg2Provider(ServiceName) to expose Angular 2 service to Angular 1
Repeat this process until all components have been converted to Angular 2