Summary This source did not publish a separate summary. Review SKILL.md before using the skill.
Angular Migration
Master AngularJS to Angular migration, including hybrid apps, component conversion, dependency injection changes, and routing migration.
Use this skill when
Migrating AngularJS (1.x) applications to Angular (2+)
Running hybrid AngularJS/Angular applications
Converting directives to components
Modernizing dependency injection
Migrating routing systems
Updating to latest Angular versions
Implementing Angular best practices
Do not use this skill when
You are not migrating from AngularJS to Angular
The app is already on a modern Angular version
You need only a small UI fix without framework changes
Instructions
Assess the AngularJS codebase, dependencies, and migration risks.
Choose a migration strategy (hybrid vs rewrite) and define milestones.
Set up ngUpgrade and migrate modules, components, and routing.
Validate with tests and plan a safe cutover.
Safety
Avoid big-bang cutovers without rollback and staging validation.
Keep hybrid compatibility testing during incremental migration.
Migration Strategies
1. Big Bang (Complete Rewrite)
Rewrite entire app in Angular
Parallel development
Switch over at once
Best for: Small apps, green field projects
2. Incremental (Hybrid Approach)
Run AngularJS and Angular side-by-side
Migrate feature by feature
ngUpgrade for interop
Best for: Large apps, continuous delivery
3. Vertical Slice
Migrate one feature completely
New features in Angular, maintain old in AngularJS
Gradually replace
Best for: Medium apps, distinct features
Hybrid App Setup
// main.ts - Bootstrap hybrid app
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { UpgradeModule } from '@angular/upgrade/static';
import { AppModule } from './app/app.module';
platformBrowserDynamic()
.bootstrapModule(AppModule)
.then(platformRef => {
const upgrade = platformRef.injector.get(UpgradeModule);
// Bootstrap AngularJS
upgrade.bootstrap(document.body, ['myAngularJSApp'], { strictDi: true });
});
// app.module.ts
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { UpgradeModule } from '@angular/upgrade/static';
@NgModule({
imports: [
BrowserModule,
UpgradeModule
]
})
export class AppModule {
constructor(private upgrade: UpgradeModule) {}
ngDoBootstrap() {
// Bootstrapped manually in main.ts
}
}
Component Migration
AngularJS Controller → Angular Component // Before: AngularJS controller
angular.module('myApp').controller('UserController', function($scope, UserService) {
$scope.user = {};
$scope.loadUser = function(id) {
UserService.getUser(id).then(function(user) {
$scope.user = user;
});
};
$scope.saveUser = function() {
UserService.saveUser($scope.user);
};
});
// After: Angular component
import { Component, OnInit } from '@angular/core';
import { UserService } from './user.service';
@Component({
selector: 'app-user',
template: `
<div>
<h2>{{ user.name }}</h2>
<button (click)="saveUser()">Save</button>
</div>
`
})
export class UserComponent implements OnInit {
user: any = {};
constructor(private userService: UserService) {}
ngOnInit() {
this.loadUser(1);
}
loadUser(id: number) {
this.userService.getUser(id).subscribe(user => {
this.user = user;
});
}
saveUser() {
this.userService.saveUser(this.user);
}
}
AngularJS Directive → Angular Component // Before: AngularJS directive
angular.module('myApp').directive('userCard', function() {
return {
restrict: 'E',
scope: {
user: '=',
onDelete: '&'
},
template: `
<div class="card">
<h3>{{ user.name }}</h3>
<button ng-click="onDelete()">Delete</button>
</div>
`
};
});
// After: Angular component
import { Component, Input, Output, EventEmitter } from '@angular/core';
@Component({
selector: 'app-user-card',
template: `
<div class="card">
<h3>{{ user.name }}</h3>
<button (click)="delete.emit()">Delete</button>
</div>
`
})
export class UserCardComponent {
@Input() user: any;
@Output() delete = new EventEmitter<void>();
}
// Usage: <app-user-card [user]="user" (delete)="handleDelete()"></app-user-card>
Service Migration // Before: AngularJS service
angular.module('myApp').factory('UserService', function($http) {
return {
getUser: function(id) {
return $http.get('/api/users/' + id);
},
saveUser: function(user) {
return $http.post('/api/users', user);
}
};
});
// After: Angular service
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
@Injectable({
providedIn: 'root'
})
export class UserService {
constructor(private http: HttpClient) {}
getUser(id: number): Observable<any> {
return this.http.get(`/api/users/${id}`);
}
saveUser(user: any): Observable<any> {
return this.http.post('/api/users', user);
}
}
Dependency Injection Changes
Downgrading Angular → AngularJS // Angular service
import { Injectable } from '@angular/core';
@Injectable({ providedIn: 'root' })
export class NewService {
getData() {
return 'data from Angular';
}
}
// Make available to AngularJS
import { downgradeInjectable } from '@angular/upgrade/static';
angular.module('myApp')
.factory('newService', downgradeInjectable(NewService));
// Use in AngularJS
angular.module('myApp').controller('OldController', function(newService) {
console.log(newService.getData());
});
Upgrading AngularJS → Angular // AngularJS service
angular.module('myApp').factory('oldService', function() {
return {
getData: function() {
return 'data from AngularJS';
}
};
});
// Make available to Angular
import { InjectionToken } from '@angular/core';
export const OLD_SERVICE = new InjectionToken<any>('oldService');
@NgModule({
providers: [
{
provide: OLD_SERVICE,
useFactory: (i: any) => i.get('oldService'),
deps: ['$injector']
}
]
})
// Use in Angular
@Component({...})
export class NewComponent {
constructor(@Inject(OLD_SERVICE) private oldService: any) {
console.log(this.oldService.getData());
}
}
Routing Migration // Before: AngularJS routing
angular.module('myApp').config(function($routeProvider) {
$routeProvider
.when('/users', {
template: '<user-list></user-list>'
})
.when('/users/:id', {
template: '<user-detail></user-detail>'
});
});
// After: Angular routing
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
const routes: Routes = [
{ path: 'users', component: UserListComponent },
{ path: 'users/:id', component: UserDetailComponent }
];
@NgModule({
imports: [RouterModule.forRoot(routes)],
exports: [RouterModule]
})
export class AppRoutingModule {}
Forms Migration <!-- Before: AngularJS -->
<form name="userForm" ng-submit="saveUser()">
<input type="text" ng-model="user.name" required>
<input type="email" ng-model="user.email" required>
<button ng-disabled="userForm.$invalid">Save</button>
</form>
// After: Angular (Template-driven)
@Component({
template: `
<form #userForm="ngForm" (ngSubmit)="saveUser()">
<input type="text" [(ngModel)]="user.name" name="name" required>
<input type="email" [(ngModel)]="user.email" name="email" required>
<button [disabled]="userForm.invalid">Save</button>
</form>
`
})
// Or Reactive Forms (preferred)
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
@Component({
template: `
<form [formGroup]="userForm" (ngSubmit)="saveUser()">
<input formControlName="name">
<input formControlName="email">
<button [disabled]="userForm.invalid">Save</button>
</form>
`
})
export class UserFormComponent {
userForm: FormGroup;
constructor(private fb: FormBuilder) {
this.userForm = this.fb.group({
name: ['', Validators.required],
email: ['', [Validators.required, Validators.email]]
});
}
saveUser() {
console.log(this.userForm.value);
}
}
Migration Timeline Phase 1: Setup (1-2 weeks)
- Install Angular CLI
- Set up hybrid app
- Configure build tools
- Set up testing
Phase 2: Infrastructure (2-4 weeks)
- Migrate services
- Migrate utilities
- Set up routing
- Migrate shared components
Phase 3: Feature Migration (varies)
- Migrate feature by feature
- Test thoroughly
- Deploy incrementally
Phase 4: Cleanup (1-2 weeks)
- Remove AngularJS code
- Remove ngUpgrade
- Optimize bundle
- Final testing
Resources
references/hybrid-mode.md : Hybrid app patternsreferences/component-migration.md : Component conversion guidereferences/dependency-injection.md : DI migration strategiesreferences/routing.md : Routing migrationassets/hybrid-bootstrap.ts : Hybrid app templateassets/migration-timeline.md : Project planningscripts/analyze-angular-app.sh : App analysis script
Best Practices
Start with Services : Migrate services first (easier)Incremental Approach : Feature-by-feature migrationTest Continuously : Test at every stepUse TypeScript : Migrate to TypeScript earlyFollow Style Guide : Angular style guide from day 1Optimize Later : Get it working, then optimizeDocument : Keep migration notes
Common Pitfalls
Not setting up hybrid app correctly
Migrating UI before logic
Ignoring change detection differences
Not handling scope properly
Mixing patterns (AngularJS + Angular)
Inadequate testing
Limitations
Use this skill only when the task clearly matches the scope described above.
Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
