angular-migration

Angular Migration - Guide for Migrating from AngularJS to the Angular Framework

Skill Overview

Master migration techniques from AngularJS to Angular, supporting hybrid-mode operation, progressive component conversion, and modernization of dependency injection.

Applicable Scenarios

1. Modernization of legacy AngularJS applications

Suitable for older projects still using AngularJS 1.x that need to upgrade to the modern Angular framework. Use ngUpgrade to run both frameworks in parallel and reduce migration risk.

2. Progressive upgrade for large enterprise applications

For enterprise-grade Angular applications with complex business logic and many features, provide two migration strategies: vertical slicing and horizontal layering, ensuring business continuity while completing the framework upgrade.

3. Component and service refactor/conversion

Convert AngularJS directives, controllers, and services one by one into Angular components and dependency injection patterns, while upgrading the routing and forms systems to the new architecture.

Core Features

Hybrid application mode (ngUpgrade)

Use the ngUpgrade module to run AngularJS and Angular in the same application in parallel, supporting shared bidirectional dependency injection, interoperability between components, and coordinated routing, making the migration process smooth and controllable.

Component and service conversion

Provide conversion templates and best practices for AngularJS Controllers to Angular Components, Factories to Services, covering lifecycle hooks, input/output bindings, and reactive data patterns.

Routing and form migration

Includes complete migration plans from AngularJS $routeProvider to the Angular Router, and from ng-model to Reactive Forms, supporting both template-driven and reactive form styles.

Frequently Asked Questions

How long does it typically take to migrate from AngularJS to Angular?

The migration timeline depends on project size and chosen strategy. Small applications (complete rewrite) take about 1–2 months, medium applications (progressive) about 3–6 months, and large enterprise applications may require 6–12 months. It is recommended to split the work into four phases: environment setup (1–2 weeks), infrastructure migration (2–4 weeks), feature-by-feature migration (by functional modules), and cleanup/optimization (1–2 weeks).

Should you choose a full rewrite or ngUpgrade progressive migration?

For small new projects or applications with severe technical debt, a complete rewrite can be less costly. For large production systems, ngUpgrade progressive migration is safer, allowing business continuity and continuous delivery during migration. Most enterprise applications are recommended to choose progressive migration, using a vertical slicing strategy to upgrade functional modules one by one.

In hybrid mode, can AngularJS and Angular components call each other?

Yes. ngUpgrade provides tools such as downgradeInjectable and upgradeComponent to enable bidirectional interoperability. Angular services can be downgraded for use in AngularJS, and AngularJS components can be upgraded for use in Angular. However, note that the two frameworks have different change detection mechanisms, so avoid mixing the two binding modes within the same component.