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Best tools for migrating AngularJS applications

Posted on by Rishan Solutions

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Migrating an AngularJS application to Angular can be a complex and time-consuming process. Thankfully, there are several tools and approaches that can assist with a smoother migration. These tools help in various areas, such as managing the hybrid application, migrating code incrementally, and ensuring compatibility between AngularJS and Angular components.

Best Tools for Migrating AngularJS Applications

1. ngUpgrade

ngUpgrade is the official tool provided by the Angular team to facilitate the hybrid approach of running both AngularJS and Angular components in the same application. It is ideal for applications that cannot be completely rewritten in Angular all at once.

Key Features:

  • Hybrid Application: Allows AngularJS and Angular to coexist within the same app. You can upgrade parts of your app incrementally without breaking the entire app.
  • Running Both Frameworks Together: Allows you to bootstrap Angular alongside AngularJS.
  • Component and Service Interoperability: You can use Angular components inside AngularJS views and AngularJS directives in Angular components.

How to Use:

  1. Install ngUpgrade: Install the necessary package for Angular to AngularJS interoperability.
    npm install @angular/upgrade --save
  2. Set up the Hybrid Application:
    • Bootstrap AngularJS and Angular side by side.
    • Use ngUpgrade to upgrade AngularJS components to Angular components gradually.

Example:

import { upgradeModule } from '@angular/upgrade/static';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { AppModule } from './app/app.module';
import { downgradeComponent } from '@angular/upgrade/static';
import { MyAngularComponent } from './app/my-angular-component.component';

// Downgrade Angular component to AngularJS
angular.module('myApp')
  .directive('myAngularComponent', downgradeComponent({ component: MyAngularComponent }));

// Bootstrapping AngularJS and Angular
const platform = platformBrowserDynamic();
platform.bootstrapModule(AppModule).then(() => {
  angular.bootstrap(document, ['myApp']);
});

2. Angular CLI (Command Line Interface)

While Angular CLI is not specifically built for migration, it plays a crucial role in the Angular ecosystem and assists in setting up and managing the Angular environment during migration. It helps automate tasks like setting up new Angular projects, running tests, and managing configurations.

Key Features:

  • Project Setup: Quickly sets up Angular projects for new features or services in a migration scenario.
  • Build Optimization: Helps in bundling the new Angular app to ensure that it runs efficiently in a hybrid scenario.
  • Code Generation: Can auto-generate components, services, and modules, which accelerates the process of replacing AngularJS components with Angular ones.

How to Use:

  1. Install Angular CLI: Install Angular CLI to manage your project. bashCopyEditnpm install -g @angular/cli
  2. Use CLI to Set Up Angular Modules: After setting up ngUpgrade and identifying which components to migrate, use Angular CLI to generate new components, services, etc. Example: bashCopyEditng generate component new-component

3. AngularJS to Angular Migration (Angular Update Guide)

Angular provides a migration guide specifically for AngularJS to Angular migrations. This guide is essential to understanding the migration process, required changes, and best practices.

Key Features:

  • Step-by-Step Migration Guide: The official Angular website provides a step-by-step process on how to move your AngularJS code to Angular.
  • Upgrade Strategy: It outlines whether to rewrite the application entirely or use a hybrid approach, depending on the size and complexity of your app.
  • Automated Code Analysis: Provides instructions on which tools to use to analyze the code for necessary changes.

How to Use:

You can access the official Angular Migration Guide on the Angular website:

This guide walks you through the steps, such as:

  • Preparing your application for migration.
  • Choosing between a full rewrite or incremental migration.
  • Tools for code analysis and upgrade support.

4. TypeScript Migration Tools

When migrating from AngularJS to Angular, a critical step is adopting TypeScript. Angular heavily relies on TypeScript, and migrating AngularJS code to TypeScript is a key aspect of the process.

Tools:

  • ts-migrate: A tool that helps you migrate your AngularJS code to TypeScript by providing code completion and error checking.
  • tslint: Helps identify coding issues and style violations during the migration, ensuring better code quality when moving to TypeScript.

How to Use:

  1. Install TSLint for TypeScript Migration: TSLint can be configured to detect issues in your JavaScript code and guide the migration process to TypeScript.
    npm install tslint --save-dev
  2. Use ts-migrate or Manually Add TypeScript Types: TypeScript migration typically involves manually adding type definitions for your code or using ts-migrate to automate some parts of the migration.

5. AngularJS Batarang (for Debugging)

While not a direct migration tool, AngularJS Batarang is a browser extension (for Chrome) that helps developers debug AngularJS applications. It is useful in diagnosing issues in your AngularJS code before migrating, allowing you to fix problems that might otherwise complicate the migration process.

Key Features:

  • Performance Profiling: Helps you understand how well your AngularJS application is performing.
  • Scope Hierarchy Viewer: Provides a view of the $scope objects, helping you trace data bindings and scope issues.
  • Debugging Directives and Components: You can inspect AngularJS components and directives to get an insight into their behavior, which can help while planning your migration to Angular.

How to Use:

  1. Install the Batarang Extension: Install the Batarang extension in your Chrome browser for easy inspection. AngularJS Batarang on Chrome Web Store
  2. Use Batarang to Inspect AngularJS App: Use the extension to analyze the scope, components, and performance of your app.

6. ngMigration Assistant (for Migration Planning)

The ngMigration Assistant is a tool provided by the Angular team that helps with the planning phase of migration. It provides insights into the complexity of your AngularJS code, points out areas that require changes, and helps plan the migration approach (full rewrite or incremental migration).

Key Features:

  • Code Analysis: Automatically scans your AngularJS codebase and identifies which parts need migration.
  • Migration Strategy: Helps determine whether you should migrate incrementally or rewrite the app.
  • Reports and Insights: Generates reports on the state of your application and the complexity of migrating various features.

How to Use:

  1. Install the ngMigration Assistant: You can use the ngMigration Assistant via the Angular CLI. npm install -g @angular/ng-migration-assistant
  2. Run the Migration Assistant: Use the assistant to analyze your app and generate a migration strategy. ng-migrate --analyze

7. AngularJS to Angular Migration Libraries

  • ng2-upgrade: A set of utilities that help with upgrading AngularJS applications to Angular.
  • ngUpgrade (Angular 2+): A utility library to make AngularJS and Angular work together smoothly.
  • @angular/upgrade/static: Specifically designed for upgrading AngularJS apps to Angular while allowing AngularJS components to be used in Angular.

8. Code Coverage and Linting Tools

When migrating, ensure that your application maintains its functionality. Tools like Jest, Karma, and Protractor can be used to test the application before and after migration. ESLint can also help in analyzing the code quality during the migration process.

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