angular-migration

# 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 ```typescript // 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 }); }); ``` ```typescript // 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 ```javascript // 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); }; }); ``` ```typescript // 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 ```javascript // 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> `, }; }); ``` ```typescript // 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 ```javascript // Before: AngularJS service angular.module("myApp").factory("UserService", function ($http) { return { getUser: function (id) { return $http.get("/api/users/" + id); }, saveUser: function (user) { return $http.post("/api/users", user); }, }; }); ``` ```typescript // After: Angular service import { Injectable } from "@angular/core"; import { HttpClient } from "@angular/common/http"; import { Observable } from "rxjs"; @Injectable({ providedIn: "root", }) export class UserService { constructor(private http: HttpClient) {} getUser(id: number): Observable<any> { return this.http.get(`/api/users/${id}`); } saveUser(user: any): Observable<any> { return this.http.post("/api/users", user); } } ``` ## Dependency Injection Changes ### Downgrading Angular → AngularJS ```typescript // 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 ```typescript // 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: ['$injector'] } ] }) // Use in Angular @Component({...}) export class NewComponent { constructor(@Inject(OLD_SERVICE) private oldService: any) { console.log(this.oldService.getData()); } } ``` ## Routing Migration ```javascript // Before: AngularJS routing angular.module("myApp").config(function ($routeProvider) { $routeProvider .when("/users", { template: "<user-list></user-list>", }) .when("/users/:id", { template: "<user-detail></user-detail>", }); }); ``` ```typescript // 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.