angular-migration

name angular-migration description Migrate from AngularJS to Angular using hybrid mode, incremental component rewriting, and dependency injection updates. Use when upgrading AngularJS applications, planning framework migrations, or modernizing legacy Angular code. Angular Migration Master AngularJS to Angular migration, including hybrid apps, component conversion, dependency injection changes, and routing migration. When to Use This Skill 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 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 {} Additional patterns and templates More detailed templates and worked examples live in references/details.md . Read that file for the full pattern library.