Modernizing AngularJS Applications with Ivy and Ahead-of-Time Compilation

Introduction

When AngularJS entered a three-year long-term support phase in 2018, it was clear that product owners had to plan for what would happen after that, i.e., beyond December 2021. They had to figure out if it was time to migrate to a new framework? Or should they have stuck with AngularJS for some more time? This is what I observed:

• The first of those projects that chose to migrate to a newer framework (like Angular) required easy, rapid, and continuous integration of modern functionalities.
• Contrarily, projects that moved slower (and are still in the process) were extensive and complex, requiring rethinking of the entire business logic, maybe with a micro-frontend approach that would enable developers to update AngularJS apps incrementally.

Regardless of the pace, the ultimate solution was to migrate to a modern, more robust framework that eventually turned out to be Angular (for the majority). In this write-up, I’ve shared some highlights, starting with why you should move from AngularJS, what changes when you migrate to Angular, and how you can do it.

Why Should you Upgrade AngularJS Apps?

There are several reasons why the majority of businesses are upgrading AngularJS apps and migrating to Angular. Some of them include:

1. End of Support for AngularJS

Despite having decided to release the final updates for AngularJS back in 2018, Google extended its long-term support until December 31, 2021 (because of the pandemic), when the support officially ended. This implies that AngularJS apps no longer receive security patches or code fixes.

2. Lack of Compatibility with Modern Web Standards and Tooling

As you know, modern web development is largely based on modular architectures, emphasizes reusable components, and requires real-time state management. However, being a decade-old framework, it lacks several features that make all of the above happen. For example, it lacks TypeScript support for efficient coding and still relies on scope-based state management, making development outdated.

3. Performance and Maintainability Issues

AngularJS is no longer efficient for modern applications that require high and consistent performance. One reason is this framework’s two-way binding cycles, which scan and update the entire variable scope whenever a change occurs. This process becomes increasingly slow as the app scales, leading to UI lags.

Moreover, when AngularJS was launched, monolithic app architectures with controllers and established scope hierarchies were largely in use. This led to codebases that were difficult to maintain, particularly as the app grew.

4. No Mobile Optimization

This framework was designed and developed way before mobile optimization became an important part of application development projects. Intuitively, it lacks the necessary built-in offerings, such as native development toolkits, support for offline functionality, efficient rendering engines/mechanisms, limited gesture handling features, etc. And in today’s mobile-first world, lacking mobile optimization is equivalent to failure.

From AngularJS to Angular: What Changed?

Owing to the above inefficiencies, Google released a better, more sophisticated development framework— Angular. Let’s see why Angular turned out to be an upgrade.

How Do These Enhancements Benefit Developers and Businesses?

For developers, this translates to:

• Easier and faster development with CLI-based automation
• Better code quality with efficient, real-time debugging
• Reduced manual effort in setting up coding environments

For businesses, this translates to:

• Quicker market entry, positioning them for a first-mover advantage
• Lower maintenance costs with effortless debugging and maintainable final codebases
• Easy scaling scope with modern tooling support
• Better security and compliance with built-in features for threat and vulnerability handling

How to Modernize/Upgrade an AngularJS App?

Even typically, migration should be done only after you have a detailed strategy/roadmap that outlines key milestones, processes, approaches, and an expected timeline. Having this strategy will minimize risks and ensure a smooth transition. Instead of rewriting the entire application at once, it is advisable to migrate incrementally. Here is a detailed breakdown of how you can migrate to Angular.

1. Devise a Detailed Strategy to Migrate to Angular

Examine your existing app—its code structure, dependencies, etc., and determine the following:

• Coupled components and outdated third-party integrations,
• Whether you want a scripting overhaul or upgrade in segments. While smaller, less complex apps may benefit from a full rewrite,
• upgrading incrementally is ideal for larger Angular applications.
• Take note of key functionalities that have to be migrated.
• Plan and set up a framework to test your Angular app. This will ensure stability throughout the process.

2. Prepare for Migration

Before ultimately migrating to Angular, update your existing AngularJS app to 1.8.3. This is the last stable version, and it also offers better support for hybrid migration via ngUpgrade. Once this is done, get rid of deprecated APIs, unused services, and redundant dependencies.

3. Move to TypeScript

Prefer migrating your AngularJS app to TypeScript before finally moving to Angular. Install TypeScript using this command:

Then, start refactoring JavaScript files. This also includes converting controllers, services, and directives.

Once this is done, introduce ES6 modules to ensure each module is self-contained, making the entire codebase more organized. You can do this by implementing the following:

• Converting global variables into importable modules
• Refactoring certain components as per ES6 class syntax
• Converting directives to use ES6 exports

4. Migrating to Angular

Now that you have updated the AngularJS application by refactoring it into TypeScript and ES6 modules, the next step is migrating to Angular. This can be done using ngUpgrade.

1. Set up a new Angular project inside your AngularJS app.

• Install Angular CLI
• Move this project into the existing codebase
• Install ngUpgrade

2. Bootstrap Angular: Modify main.ts (the main TypeScript code) to use Bootstrap.

3. Start incremental migrations.

• Convert an Angular component for use in AngularJS using new-button.component.ts
• Downgrade the component using app.module.ts

4. Upgrade AngularJS services to Angular services.

5. Migrate Routing to Angular Router.

• Set up Angular Routing using app-routing.module.ts
• Modify index.html to use Angular Routing
• Migrate all Routes one by one using ngUpgrade to handle redirection between the two routers.

5. Remove AngularJS Dependencies & Fully Switch to Angular

Once you have refactored and moved all functionalities, dependencies, services, and routes to Angular, finalize the transition and

remove the old AngularJS version by:

• Removing the Bootstrap code by deleting angular.bootstrap(document, ['myAngularJSApp']
• Uninstalling all AngularJS packages
• Running final performance tests
• Removing ngUpgrade, legacy controllers, and unused dependencies from the legacy code

Modernization Pitfalls: Challenges in Upgrading AngularJS Apps

There is no question as to whether you should update your AngularJS application and switch to Angular. However, the process might be difficult, particularly if you lack the necessary technical support. The following AngularJS modernization issues could arise:

1. Difficulties with Architectural Overhaul

Moving from an MVC architecture to a modular one requires considerable refactoring of tightly coupled components and outdated logic into reusable elements. Moreover, moving from AngularJS’ two-way binding to Angular’s unidirectional data flow makes the entire process more taxing and time-consuming.

The Result: Overwhelmed developers and delayed processes often add to the costs.

2. Skill Gaps: Developers Who Can Work with Both TypeScript and RxJS

As AngularJS is built on legacy JavaScript and Angular uses TypeScript, migrating would require skilled developers who are proficient in scripting application logic with both. While JavaScript is widely used, finding expertise in TypeScript is often relatively more challenging because of the learning curve for reactive programming and modular development.

The Result: Delayed modernization that makes your app outdated.

3. Handling Third-Party Dependencies

Many third-party libraries that are often integrated with AngularJS apps are incompatible with Angular or have been discontinued. Consequently, these will have to be replaced or replicated through custom API development and integration, causing disruptions in your migration process.

The Result: Expensive supplemental development that eats into your modernization budgets.

4. Potential Downtime and Delays

Moving from AngularJS to Angular is not a simple version upgrade but a complete overhaul, and a poorly planned migration strategy can cause serious deployment failures. It can result in application downtime, break business logic, and even lead to data inefficiencies and loss. In worst-case scenarios, the entire application may need to be taken offline until the issues are resolved.

The Result: Loss of consumer trust and loyalty because of disrupted user experience.

The Right Approach: Angular Expertise

Addressing the challenges of migrating from AngularJS to Angular requires skilled expertise and the right execution model. This is often done by hiring dedicated AngularJS developers, allowing for full-time focus and tailored development while still giving you complete project control. You can also consider outsourcing the entire project to a reliable service provider to benefit from scalability, cost efficiency, and expert-led execution without long-term commitments.

In fact, with more than 42% of C-suite executives finding competing priorities a major roadblock in modernizing applications, working with external experts can be an effective solution to overcome these challenges eventually.

Let’s discuss the two approaches.

1. Hiring Experienced Angular Developers

If you already have development teams working on multiple projects, hiring experienced Angular developers can help bridge the skill gap and resource constraints that you must have faced when allocating in-house developers to modernization projects. Having external developer support, in such a scenario, allows you to adopt a phased modernization/upgrade approach.

What do you get with them:

• Expertise in RxJS, TypeScript, and Angular’s component-based architecture
• Experience in handling hybrid AngularJS-Angular applications
• Ability to optimize performance and refactor outdated AngularJS logic
• Integration of modern DevOps practices for smooth deployment

This approach keeps your AngularJS modernization project under internal control. It also makes the process more sustainable in the long-term as you can easily scale up (or down) based on your desired pace and extent of modernization.

2. Outsourcing AngularJS to Angular Migration to a Professional Service Provider

For businesses that lack in-house expertise or need a faster, lower-risk modernization or migration, outsourcing Angular development is the most efficient solution. Service providers have established semi-automated workflows and dedicated teams who look after the project on your behalf.

What an Outsourced Angular Team Can Handle:

• Full end-to-end migration from AngularJS to Angular
• Refactoring controllers, directives, and services into Angular components
• Ensuring compatibility with third-party dependencies
• Devising and implementing a zero-downtime migration plan

While it comes with a considerable upfront cost, this approach is often cost-efficient in the long term as you’re free from hiring, onboarding, and managing AngularJS (or Angular) developers. The execution is also faster and readily compliant with development best practices, ensuring the modernized application surpasses all performance standards. However, there’s a drawback: you have limited control over the project, as the onus of completing this project lies with the service provider.

Ready to Modernize your AngularJS App?

Being open to technological advancements is the only way to continue succeeding today. Conversely, if you stick with your legacy systems and frameworks—such as AngularJS in this case—you’ll likely fall behind competitors who perform much better in terms of maintainability, scalability, security, and performance. Modernization provides a complete overhaul of your apps by transitioning to modern, modular architectures, making it a proven strategy to invest in if you want to mitigate long-term technical debt. Whether you choose an incremental transition or a full migration, do it internally, or outsource it to Angular developers, the key is to plan strategically for sustainable growth.