Strategies to upgrade to Angular

There are different upgrade strategies available to migrate to Angular. They are as follows:

• One time: Replacing the entire AngularJS app, rewriting the code in Angular starting at one point.
• Incremental: Upgrading the existing app one service or component at a time, running AngularJS and Angular side by side.

If the AngularJS app is small, then rewriting at one time is probably the easiest and fastest way to upgrade. If the AngularJS app is larger and can't rewrite the whole code at once, we need to rewrite step by step, component by component, service by service. This is called incremental upgrading. However, running ng1 and ng2 side by side has performance implications.