Using ng-upgrade (Angular 1.x Co-Existing With Angular 2)

The ng-upgrade is done by running Angular 2 and Angular 1 together in the sameapplication. In this scenario Angular 1.x controls the page, and Angular 2controls the change detection mechanisms. Once the two Angulars co-exist,upgrading can be done in strategic pieces.

原文: https://angular-2-training-book.rangle.io/handout/migrate/ng-upgrade/