Running AngularJS and Angular side by side is a common approach during the migration process from AngularJS to Angular. This method allows developers to incrementally upgrade their applications without needing to rewrite the entire application at once. Here’s how you can achieve this:
1. Using the UpgradeModule
The UpgradeModule from Angular is specifically designed to facilitate the coexistence of AngularJS and Angular within the same application. This module allows you to bootstrap both AngularJS and Angular applications and enables the interaction between components written in both frameworks.
Bootstrap Hybrid Application: You start by bootstrapping both the AngularJS and Angular applications. This is done by configuring the AngularJS application to bootstrap manually rather than automatically, and then bootstrapping the Angular application which in turn bootstraps the AngularJS application[2][3][5].
Downgrade/Upgrade Components: Angular provides the ability to 'downgrade' Angular components so they can be used in AngularJS or 'upgrade' AngularJS components so they can be used in Angular. This is done using the downgradeComponent and UpgradeComponent utilities respectively[1][2].
2. Dual Booting
This approach, also known as dual booting, involves running both AngularJS and Angular frameworks in the same application during the migration phase. It allows parts of the application to be upgraded incrementally[3].
Separate Configuration: You maintain separate configurations for AngularJS and Angular. This might involve different build setups or entry points in your application where both frameworks are initialized[3].
3. Using ngUpgrade
ngUpgrade is a library that provides a robust way to mix and match AngularJS and Angular components and services. It supports the incremental upgrade strategy by allowing AngularJS and Angular to coexist in the same application[1][5].
Incremental Upgrading: You can upgrade services and components piece by piece. Angular services can be made available to AngularJS components through dependency injection and vice versa[5][11].
4. Practical Steps
Here are some practical steps to implement this hybrid approach:
Prepare AngularJS Application: Refactor the AngularJS application to make it more mo...
