Table of content


he fact that Google plans to get rid of AngularJS smoothly became known back in 2018. Exactly two years after the release of Angular 2. However, despite such news, many companies were still in no hurry to start the migration AngularJS to Angular. The death of Angular.js didn't seem like something critical to web project owners. Alternatively, they were worried the second version of Angular would meet the fate of the first one after a while. We can only guess about it.

Now, everyone who still maintains their web products built on a JavaScript-based framework has a hard time. They must either urgently begin the migration AngularJS to Angular, develop a new web product from scratch, or choose a suitable Angular.js alternative. If you've got here, chances are you've chosen the first option and want to know about how to prepare for this process. In today's blog post, our Angular development team will tell you everything you need to be aware of before starting the migration.

Extend your team with niche-experienced developers today!

Book the call with our Managing Partner

book the call

Choose your path first: The migration essentials

One of the first things to do before upgrading your legacy JavaScript-based project is to choose a migration method. The choice determines the whole further sequence of actions in prep for the migration AngularJS to Angular.

Which choices are open to you?

  1. Hybrid migration method.
  2. The parallel migration method.

Think twice before you go on the attack. It's a crucial step, that may even affect the future of your business. You should consider all the risks before writing a plan to get ready for the platform upgrade.

When the hybrid method is used:

  • You have a large-scale web application with many features that takes many time to maintain; 
  • You can't afford to disable web access for your customers suddenly, and you don't want to allow the web product to fail;
  • You don't have a huge development team, so you want to make the switch gradually and efficiently;
  • You've found a team of experts to help you get the job done.

Still, you should be prepared to spend a specific budget on the migration AngularJS to Angular and be ready for all sorts of difficulties. For example, you will have to perform many tests, fix bugs, and deal with problems like a dynamic compilation from the line.

Case in point: There were no problematic situations related to the upgrade of web projects in our practice. However, our ears have heard a story from a well-known online platform for learning English. Several years ago, the creators of the web service decided to improve it and move to a more recent version of Angular. The team took for dynamic compilation for Angular.js, which has the form: 

const compiledContent = this.$compile(template)(scope);


Then they ran this piece through the JiT compiler. The problem was that even with AoT compilation, some of the dynamic templates were heavy. The page worked, but it took 6 seconds to compile. Moreover, for 3 of those seconds, nothing happened at all. The team had to try four solutions before they found the right one.

In which scenarios the parallel method is used:

  • You have a relatively small app, and it won't take you long to create a new Angular-based version;
  • You want to get a stable web project version out of the box and forget about Angular.js issues forever;
  • You don't need to maintain an existing web product 24/7, so you can focus the attention of your development team on building a new project.

Like the previous method, this model of the migration AngularJS to Angular also has its difficulties. For example, you have to go through the same stages of development again as with a JavaScript-based web product. You need to think through the architecture and logic of the web application, do numerous tests, clean up bugs, find better solutions to improve performance, etc. For some companies, it's not only expensive but an exhausting process.

Instructions on how to handle the hybrid migration model preparations

We don't know which option you're going to use for the migration AngularJS to Angular, so we've prepared two scenarios. Let's start with what you need to do to create a hybrid app.

Note: Depending on the specs of your product and industry, the actual number of steps will vary. Instructions to prepare for the upgrade may not be the same for all web projects. Contact us to schedule an evaluation of your web product and discuss our next steps.

A step-by-step preparation algorithm for the migration AngularJS to Angular

  1. At this stage, you need to use a particular package with AngularJS type definition and implement compile options or configure the use of TS (TypeScript) code in advance. Our team typically uses the most common and suitable package for this purpose called @types/angular. It's necessary to ensure that programmers have less to worry about when putting together the AngularJS to Angular migration plan. The npm package can help you quickly tweak the TS code to seamlessly make the JS (JavaScript) code compatible. All you have to do is utilize the allowJs compiler feature.
  2. Now you should tidy up your code. Get rid of all unnecessary things using the latest changes in the JS programming language or take tips from Angular.js Style Guide for this. So you can avoid bloody battles like between Tab or Space-style programmers in your crew. When you have an all-in-one guide, you won't have to debate whether or not a particular solution is appropriate in cleaning up old code.
  3. An equally important step in preparing for the migration AngularJS to Angular is to cut out the $scope object. Developers need to carefully review the source code structure and modify it with the $scope dropped out. The second and later versions of Angular no longer have this concept.
Note: The best way is to do a hybrid migration gradually. You'll have fewer crutches and thin-necks in the process by doing so. It's the official recommendation of the Angular coding team. You can jump several versions of the TypeScript-based front-end framework; however, you must be prepared for all sorts of complexities then.
  1. Our team must warn you that this step is unsuitable for all web projects. Nevertheless, if your product can use the component API, apply it as many times as possible. This API has been available since version 1.5 and is very similar to what we started using in version 2. If your project was built specifically with the Angular.js 1.5+ framework, you're in luck. Even if not, you don't necessarily need to despair and panic. It's enough to move on to the next stage of upgrade preparations.
  2. The last step is to pick libraries and tools offered by the official JavaScript-based framework team. At this point, the development crew needs to choose and align the instruments required to connect parts of the old and new code, creating a viable hybrid web app or website. The ngUpgrade library is widely considered the most favored. It's pretty good for this purpose, but besides it, the team often utilizes other proven libraries to achieve perfect code compatibility.

Probably it is the most comprehensive plan of preparation for the migration AngularJS to Angular now. In rare cases, other instruments are added here, but the number of steps is generally equal to 4-5. 

Tips on how to prepare for the migration AngularJS to Angular in parallel

Since there is no official guide for this upgrade model, it's pretty difficult to put together a step-by-step instruction as a cheat sheet. So, the team shares a couple of tips on where to start preparing for the migration AngularJS to Angular.

Our pro tips

  1. Hire a team of talented Angular developers. Qualified specialists with solid backgrounds will help you develop the best plan for creating a web project. It is preferable to choose programmers who have worked with products in your industry and know the specifics of a particular market.
  2. Prepare with the crew the architecture and the logic of the web project. Besides the front-end devs, you will need back-end coders in the command. Working closely as one, the experts can achieve a flawless performance for the project, both on the client-side and the user-side.
  3. Set up the necessary tools and choose a kit of required add-ons. You will need to install Node.js, TypeScript, and Angular CLI for a smooth experience. You'll also have to pick routing and testing tools, servers, libraries, browser extensions, and more.
  4. Build a professional staff team to beta-test the web product. You have to pre-select a focus group and QA specialists who can spot even the unnoticeable flaws of the new application. You can only shut down an AngularJS-based project thoroughly after prosperous and numerous tests.

These are the main guidelines on how to prepare for the parallel migration AngularJS to Angular model. Well, there is plenty of routine work waiting for you even before starting the development. After all the hassle and expense, you will get a 100% working app without parts of legacy code. If you don't like Frankensteins, as hybrid apps are sometimes called, it's worth following this way of project development.

A brief conclusion on preparing for the migration of AngularJS to Angular

As you can see, you need preparation to properly migrate your web project from Angular 1 to one of the Angular 2+ versions. Only cohesive steps will help you achieve your goal, avoiding possible difficulties.

Lack of preparations leads to the following unwanted effects:

  1. You can make fatal slip-ups in the development time calculations. If the mistake is made for the hybrid migration AngularJS to Angular model, such inaccuracies will not be catastrophic. Still, it is hard for the parallel model to miscalculate the timing for the parallel model. For one thing, not every company can afford to hire two development teams. The first team to maintain AngularJS-based version and the second one to write the code for the project from scratch. Another thing, you will have to abandon the working version of the project for some period, preceding the updates and improvements of the platform. It may not have the best effect on your customers' service, their comfort, and your revenue.
  2. You can choose an unsuitable toolkit and libraries. There are versatile tools for the upgrade platform that you can use. It would be best if you did not forget about the specifics of different projects, the logic of their work, etc. Even if you are not engaged in development yourself but hire an Angular developer, it is beneficial to research the topic beforehand.
  3. You can make critical mistakes that will take hours and hours to fix. Incorrect tasking of the team or insufficiently thought out roadmap for development leads to serious and non-serious bugs. For business, this is fraught with the risk of doubling the programmers' working hours, making the web application's functionality fail or work too sluggish.

In the upcoming articles on the migration of AngularJS to Angular, we'll take a closer look at the choice of tools, step-by-step instructions for the hybrid transition model, and much more. A series of blog posts related to this topic can help you better understand the workflow steps and apply them to your project as needed. If you still have any questions about preparing for the upgrading, book a call with our Managing Partner or email

Rate this article!
ratings, average:
out of 5
December 30, 2021
AngularJS to Angular

Read also

View All
No items found.

More from 

AngularJS to Angular


View All