Belitsoft > Angular Development > AngularJS to Angular Migration

AngularJS to Angular Migration [Full Guide]

AngularJS framework stops being supported. And if you decide to add new features or upgrade your AngularJS-based app, you may struggle to find the right specialist. The reason is developers hone their skills at new technologies to stay in demand. And few developers are now able to work with old technologies like AngularJS. So if you’re considering AngularJS to Angular migration now or later, keep on reading to find out: How will your app benefit from such a transition? What is the best migration path for you (+ best migration path analyzer)? Or maybe alternative options like React or VueJS will be a better fit for you (comparison table included)?


Difference between Angular and AngularJS

Just a quick remark to dot the i's for the question “Is Angular and AngularJS the same?”:

AngularJS is the name for all 1.x versions of Angular released before 2018. While Angular is the name for all Angular 2.x versions of today and tomorrow.

AngularJS is a feature-rich framework. However, as any old technology, AngularJS falls behind more up-to-date frameworks, such as Angular.

Vincent T. ,the UI Engineer at Mozilla, shares:
"I was a very satisfied user of Angular.js, and if you have a project in it currently, I'm sure it works just fine. But you're also missing out on a whole lot if you're restricted to their now-clumsy module system, their now-clumsy unit testing setup, their custom syntax with no editor support, its limited ability to work with type checking... All those are fine not to have for an existing project, but they're what make people choose other frameworks (such as Angular 2+) for new projects. Angular.js wouldn't have been as big as regular Angular is today if they'd have kept focusing on that - let alone as big as React".

Why Should I Migrate from AngularJS to Angular?

Elana Olson, the former developer at Google who worked on the Angular team to streamline the process of upgrading from AngularJS to Angular lays out the major benefits of the migration.

Fast Performance and App Scalability

Angular is highly scalable due to its modular architecture with reusable pieces of data. Each piece is responsible for a certain feature and remains independent within the entire system.

On top of that, developers can learn one way to build applications. Then, a developer can just swap one component with another without rewriting the entire code.

"Angular was created for three key reasons - scalability, runtime performance, and modernizing with the web. When AngularJS applications began to scale to become large applications, the small cracks that were only minor annoyances became full-blown problems. Likewise, the runtime performance began to diminish".
Elana Olson, the specialist from the Angular team

Angular ensures the fast performance of your application thanks to the use of Web Workers and server-side rendering.

Besides, some packages (for example, animations) were removed from the main Angular core for faster performance. If needed, they can be added.

Reduced runtime errors

TypeScript has an advanced type-checking feature. This feature allows detecting most bugs at build time instead of runtime. Enhanced error reporting and ahead-of-time (AOT) compilation also contribute to reducing runtime errors.

"[We] added types using TypeScript to reduce errors... We want to help you [developers] at every stage of building an application".
Elana Olson,the specialist from the Angular team

Rich Tooling for Building Amazing Apps

With Angular, there is no need to use and pay for third-party tools, as it comes with a package of the necessary tools.

For example, the Command Line Interface (CLI), Integrated Development Environment (IDE), and text editors.

"Build features quickly with simple, declarative templates. Extend the template language with your own components and use a wide array of existing components. Get immediate Angular-specific help and feedback with nearly every IDE and editor. All this comes together so you can focus on building amazing apps rather than trying to make the code work".
Elana Olson, the specialist from the Angular team

On top of that, Angular offers rich tooling for application testing by means of unit tests and e2e tests, built-in test modules for fast test coverage.

The awesome Angular Material UI framework that is easily customizable can be installed as a separate module with a rich set of UI components and LTS support.

Mobile Support

Today, if you are not developing a mobile version of your app today, you are leaving money on the table. Statista report proves this:

"54.8% of the global browsing was performed using mobile devices in the first quarter of 2021".

Angular developers implemented 2 key changes to go mobile:

  1. Angular-based apps load particular modules only when they are needed (Lazy Scripting).
  2. The apps are rendered on Angular Universal service instead of a client browser to reduce the page load time.

Support and regular updates

Angular is an up-to-date technology with strong support and regular updates. The large community of Angular developers promises to release new improved versions every 6 months. This will ensure your Angular-based app to evolve and scale meeting the fast-growing demands of app users.

Besides, Google announced Long-Term Support (LTS) for the technology. This means that Google plans to stick with the Angular ecosystem and further develop it, trying to hold the leading positions among front-end engineering tools.

The number of experts who still work with AngularJS is getting lower and lower. We have a team of specialists who are ready to implement the AngularJS to Angular migration plan for your app smoothly and at a reasonable cost. Contact us to get more details.

How Can We Migrate AngularJS to Angular?

The developer from Google Angular team suggests the following migration paths as the most viable and time-proven ones:

  • updating through ngUpgrade,
  • updating through Angular elements,
  • routing,
  • or rewriting from scratch.
AngularJS to Angular migration AngularJS to Angular migration paths

Rewriting from Scratch

Direct rewrite may be an option when you have decided to make AngularJS upgrade to Angular. It allows you to refactor an app and try new techniques.

When to choose: for small and medium apps.

Pros: Rewriting may include restructuring, refactoring, redesigning your application, or removing unnecessary code. This is feasible when:

  • You want to build an app differently this time and implement better practices along the way.
  • You need more freedom in adding new features and making significant improvements.

Cons: During a certain period of time you will have to maintain two versions of the app for a smooth transition. And maintaining two versions requires more time, money, management, and support efforts.

Incremental Updating

The incremental approach to migrating implies upgrading one section of your app at a time. In this case, AngularJS and Angular interoperate seamlessly for some time. As a result, you're gradually replacing old AngularJS features and building new features in Angular.

When to choose:

  1. for upgrading large and complex applications without disrupting business.
  2. if you need to continue releasing new features while slowly migrating from AngularJS to Angular.

Before starting the upgrade, you need to prepare and align your AngularJS application with Angular. These preparation steps are necessary for making the code more maintainable, decoupled, and aligned with modern development tools.

Method 1: ngUpgrade

NgUpgrade is a library created by the Angular team to mix and match AngularJS and Angular components.

When migrating through ngUpgrade, what you're actually doing is running both AngularJS and Angular. And you can have all the features and behavior of both frameworks.

The components and services of one framework can interoperate with those of the other framework. This can be applied in three main areas: Dependency injection, DOM, and change detection.

One of the core tools by ngUpgrade is the UpgradeModule. It contains utilities for bootstrapping and managing hybrid apps that can support Angular and AngularJS code at the same time.

Learn more about using Angular Elements in the official guide.

Method 2: Angular Elements

Angular elements is a package that allows transforming Angular components into reusable custom elements, or Web components.

When applying Angular elements, you are actually downgrading an Angular component and putting it into an AngularJS application. Thanks to this, you can replace old AngularJS components with new Angular components and build new features in Angular.

When you add custom elements to the DOM, they bootstrap automatically. When you remove them from the DOM, they are automatically destroyed. It looks and behaves like any other HTML element. It does not require any special knowledge of Angular terms or usage specifics.

Learn more about using Angular Elements in the official guide.

Method 3: Routing

Many AngularJS-based single-page applications (SPAs) are built using a router. This means that you have to migrate your router when migrating to Angular. There are two approaches to migrating the router: hybrid routing and direct change.

Hybrid routing means that your app hosts both an AngularJS router and an Angular router, eventually leading to the switch to the Angular one. This approach is used when you upgrade from the built-in AngularJS to the Angular router or through the AngularJS UI router to the Angular one.

Direct change is preferable when rewriting an app from scratch. If you want to maintain a SPA in the Angular app, you will need to switch to the built-in Angular router. It suits smaller applications that are not reliant on a hybrid state.

Learn more about routing in the official guide.

Other methods

There are less researched migration paths. The Google team cannot confirm that these solutions are well-used or still maintained. So they recommend proceeding with caution.

TIP! Try ngMigration Assistant to check which migration path is your go-to option. For that, this tool scans your AngularJS application and provides a stats report.

If you need an expert evaluation of your AngularJS app and the optimal migration approach, refer to a reliable software development company. The Angular experts will analyze your current software size, functionality, other specifics and make up a detailed AngularJS to Angular migration plan.

Alternative frameworks to migrate: React and VueJS

There's no clear winner between Angular, React, and VueJS. So we've compiled and compared the benefits and pitfalls of each technology to facilitate your choice.

General Information




Year of Creation




Supported by



Community (mostly Chinese)

Used by

Google, Paypal, Forbes, Santander, Deutsche Bank, Samsung, etc.

Amazon, Twitter, Netflix, Shopify, etc.

Alibaba, Baidu, GitLab, Grammarly, etc.

Performance Details Comparison












Package Size





Highly reusable components and directives

Reusable and declarative components

Model–view–viewmodel (MVVM)


Fits the most complex of projects.

Fits for creating dynamic, interactive UIs, often for SPAs.

Fits for building user interfaces and SPAs.

Performance specifics

The most robust. Fast refactoring, good autocompletion, and navigation.

Fast performance. Cohesive design. Reusable logic.

Easy maintenance. Refactoring isn't necessary often. Backward compatibility.


Platform-independent, with high code reusability

High code reusability

Highly adaptable and scalable

Third-Party Tools

Not needed. Data binding, routing, project generation, and form validation are already a part of the package. 

Handles only the front-end development, so other technologies must be included in the development.

Might be needed. Easily integrates with other libraries or existing projects.





Data Binding

Both unidirectional and bidirectional

Unidirectional for easy debugging and maintenance



Detailed, with code examples



Learning Curve

Difficult: many complex principles to master, much documentation to read.

Quite difficult: due to the rapid pace and large amount of updates.

Simple: requires only the basic knowledge of JavaScript, HTML, and CSS.

Choosing among Angular, React, and VueJS, opt for the one that will make your life easier.

If you're a developer, you may opt for a framework that goes well with what you already know and is highly demanded in your industry.

If you're a product owner, you might consider your resources, technology stack already in use, and the capabilities of your development team.

Now migration from AngularJS is not a question of whether to do it or not. Now it's a question of how to do it smoothly and fast and who will perform it for you. A declining number of developers is capable of supporting old systems, so now is a perfect time to act. Our team has years-long expertise in AngularJS to Angular, React, or VueJS migration. Contact our expert for a free consultation.

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