Migrating from AngularJS (1.x) to Angular (2+) is a complex process, but several tools and libraries can help make the transition smoother. These tools assist in code analysis, upgrading directives, handling routing, migrating services, and ensuring compatibility. Below are the best tools for a successful migration.
1. Official Angular Upgrade Library (ng-upgrade)
What is it?
ng-upgrade is the official Angular library that allows AngularJS and Angular to coexist in a hybrid mode, making migration gradual instead of a full rewrite.
Key Features:
Run AngularJS and Angular side-by-side.
Upgrade services, directives, and components incrementally.
Allows step-by-step migration instead of rewriting everything at once.
Installation:
npm install @angular/upgrade
Example: Upgrading an AngularJS Service to Angular
angular.module('myApp').service('UserService', function() {
this.getUser = () => ({ name: "Narendra", age: 25 });
});
Convert to an Angular Injectable Service:
import { Injectable } from '@angular/core';
@Injectable({
providedIn: 'root'
})
export class UserService {
getUser() {
return { name: "Narendra", age: 25 };
}
}
Use ng-upgrade to bridge services:
import { UpgradeModule } from '@angular/upgrade/static';
@NgModule({
imports: [UpgradeModule],
})
export class AppModule {
constructor(private upgrade: UpgradeModule) {}
}
When to Use?
✔ When a step-by-step migration is needed.
✔ If large applications require gradual upgrades.
2. AngularJS Migration Assistant (Angular CLI ng migration command)
What is it?
A tool inside Angular CLI that helps analyze AngularJS components, dependencies, and patterns that need migration.
Installation & Usage:
npm install -g @angular/cli
ng migration angularjs
Key Features:
Scans AngularJS code for potential migration issues.
Provides recommendations and best practices.
Generates reports for manual fixes.
3. @angular/cli for Bootstrapping New Angular Projects
What is it?
A command-line tool for quickly setting up Angular applications.
Installation:
npm install -g @angular/cli
ng new my-angular-app
When to Use?
✔ When rewriting an AngularJS app into a new Angular project.
✔ If the existing AngularJS code is outdated or too complex to migrate.
4. ngMigration Assistant (CLI-based Code Analyzer)
What is it?
A free CLI tool that analyzes AngularJS projects and suggests migration strategies.
Installation & Usage:
npx @angular/migration-assistant
Key Features:
Identifies deprecated APIs and AngularJS dependencies.
Detects complexity levels in controllers, services, and directives.
Suggests best migration approaches (hybrid mode, full rewrite, etc.).
5. ngMigration Forum (Community-driven Support)
A Google group and GitHub discussions where developers share migration experiences.
Link:
🔗 https://groups.google.com/g/ngmigration
Ask questions about migration challenges.
Find solutions from AngularJS experts.
6. typescript-eslint for Converting JavaScript to TypeScript
Since Angular uses TypeScript, JavaScript code needs to be converted. typescript-eslint helps identify incompatible JS syntax.
Installation & Usage:
npm install --save-dev typescript-eslint
Finds issues in old JavaScript code.
Auto-fixes errors when converting to TypeScript.
7. angular-eslint for Ensuring Code Quality
This tool enforces TypeScript best practices when rewriting AngularJS code.
Installation & Usage:
ng add @angular-eslint/schematics
Detects TypeScript linting issues.
Ensures migration follows Angular best practices.
8. RxJS for Handling Asynchronous Code
Since Angular heavily uses RxJS for handling HTTP requests, events, and state management, migrating from AngularJS $q promises to RxJS observables is crucial.
Installation:
npm install rxjs
Example: Converting $q Promise to RxJS Observable
Before (AngularJS $q promise)
angular.module('myApp').service('UserService', function($http, $q) {
this.getUser = function() {
let deferred = $q.defer();
$http.get('/api/user').then(response => deferred.resolve(response.data));
return deferred.promise;
};
});
After (Angular RxJS Observable)
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
@Injectable({
providedIn: 'root'
})
export class UserService {
constructor(private http: HttpClient) {}
getUser(): Observable<any> {
return this.http.get('/api/user');
}
}
Better performance and error handling.
Built-in retry, debounce, and error-catching mechanisms.
9. ngx-translate for Handling Internationalization (i18n)
If an AngularJS app uses custom translation services, migrating to Angular’s ngx-translate is recommended.
Installation & Setup:
npm install @ngx-translate/core @ngx-translate/http-loader
Supports dynamic language switching.
Easy migration from AngularJS $translate services.
10. Hybrid UI Libraries for AngularJS & Angular Coexistence
If migrating UI components, consider hybrid libraries that work in both frameworks:
Angular Material → Modern UI components.
Clarity Design System → Enterprise-grade UI.
Bootstrap UI → Compatible with both AngularJS & Angular.
Which Tool Should You Use?
| Tool | Best For |
|---|---|
ng-upgrade | Running AngularJS & Angular side-by-side |
ng migration | Analyzing AngularJS apps for migration |
@angular/cli | Bootstrapping new Angular projects |
ngMigration Assistant | Generating migration reports |
typescript-eslint | Converting JavaScript to TypeScript |
angular-eslint | Enforcing TypeScript best practices |
RxJS | Replacing AngularJS $q promises |
ngx-translate | Migrating translation services |
Hybrid UI Libraries | Using shared UI components in both frameworks |