Angular

Mixing Storybook with Angular with a Sprinkle of Applitools

Published Oct 28, 2019

Updated Feb 14, 2023

8 min read

This article was written over 18 months ago and may contain information that is out of date. Some content may be relevant but please refer to the relevant official documentation or available resources for the latest information.

To better understand the Applitools Storybook SDK for Angular, we will be building a small Angular application from scratch, adding some Storybook stories, and then finally performing visual regression testing using the Applitools SDK to generate snapshots for us to view and analyze.

You can find the source code for this article on GitHub by following this link storybook-angular-applitools repo.

Create Angular 7 App using the latest CLI

Make sure you have the latest Angular CLI installed. In my case, I will be using the Angular CLI v7.0.2. Create a new Angular App using the following npm command:

ng new storybook-angular-applitools

Create the ContentEditable Component

The ContentEditable component we are going to build in this section wraps an HTML <div> element and adds an HTML attribute of contenteditable=”true”. The component implements the ControlValueAccessor so that the component can be used like any other Angular form control inside HTML forms.

<div contenteditable=”true”>This is an editable paragraph.</div>

The HTML fragment above renders in the browser as an editable area that users can click and enter any text or HTML.

Create a new component file and add the following markup to contenteditable.component.html file:

<div 
 #container 
 [ngStyle]=”styles” 
 [innerHTML]=”contentValue” 
 (input)=”setContent($event)” 
 contenteditable=”true”>
 </div>

Next, add the code below to the contenteditable.component.ts file:

import { Component, ChangeDetectionStrategy, Input, forwardRef, OnChanges, SimpleChanges, ElementRef, Renderer2, ViewChild } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';

@Component({
  // tslint:disable-next-line:component-selector
  selector: 'editable',
  templateUrl: `./contenteditable.component.html`,
  styles: [],
  changeDetection: ChangeDetectionStrategy.OnPush,
  providers: [
    {
      provide: NG_VALUE_ACCESSOR,
      useExisting: forwardRef(() => ContentEditableComponent),
      multi: true
    }
  ],

})
export class ContentEditableComponent
  implements ControlValueAccessor, OnChanges {
  @ViewChild('container') container;
  private _styles: any;
  private _contentValue: any;

  propagateChange: (value: any) => void = () => {};

  @Input()
  set styles(style: any) {
    this._styles = style;
  }

  get styles(): any {
    return this._styles;
  }

  get contentValue(): any {
    return this._contentValue;
  }

  set contentValue(val: any) {
    if (this._contentValue !== val) {
      this._contentValue = val;
      this.propagateChange(val);
    }
  }

  writeValue(value: any) {
    if (value !== this._contentValue) {
      this.contentValue = value;
    }
  }

  registerOnChange(fn: (value: any) => void) {
    this.propagateChange = fn;
  }

  registerOnTouched(fn: () => void) {}

  setContent($event: any): void {
    // this._contentValue = $event.target.innerHTML;
    this.propagateChange($event.target.innerHTML);
  }

  ngOnChanges(changes: SimpleChanges): void {}
}

The component is straightforward and follows the best practices in building a ControlValueAccessor. It defines a single @Input() property to allow the consumer of this component to control its styling.

If you want to fully understand how ControlValueAccessor works in Angular check out Max’s article titled Never again be confused when implementing ControlValueAccessor in Angular.

Next, add the following HTML snippet to the app.component.html file:

<section class="section">
 <h2>Two-way Data-binding</h2>
 <editable name="editable2" [styles]="styles()" [(ngModel)]="content1"></editable>
 <pre>{ content1 | json }</pre>
</section>

Define the styles() method inside the AppComponent class:

styles() {
 return {
  "background-color": "yellow",
   margin: "10px auto",
  "max-width": "60%",
  "line-height": "25px",
  padding: "10px"
 };
}

And now run the application. You should see something similar to this below.

You can start typing in the yellow editable rectangle and you will see whatever you type underneath.

Let’s switch gears and add Storybook to the application.

Add Storybook packages

We need to add Storybook for Angular to your application. The Storybook website offers a detailed installation guide on Storybook for Angular. Once installed, apply the following changes, so that Storybook runs correctly with your Angular 7 application.

Open the src/app/tsconfig.app.json file and make sure the exclude property has the following values:

"exclude": [
  "test.ts",
  "**/*.spec.ts",
  "stories"
 ]

Open the .storybook/tsconfig.json file and paste the following:

{
 "extends": "../src/tsconfig.app.json",
 "compilerOptions": {
    "types": [
    "node"
  ]
 },
 "exclude": [
    "../src/test.ts",
    "../src/**/*.spec.ts",
    "../projects/**/*.spec.ts"
 ],
 "include": [
    "../src/**/*",
    "../projects/**/*"
 ]
}

Create and run a few Storybook stories

Add the following Storybook stories into the file located at src/app/stories/index.stories.ts:

storiesOf('ContentEditable Component', module)
 .add(
   'with yellow background',
   withNotes('Testing the background color for the editable area and setting it to yellow')(() => ({
     component: ContentEditableComponent,
     props: {
       styles: { 'background-color': 'yellow', 'padding': '20px' },
       ngModel: 'The content goes here',
       ngModelChange: action('ngModelChange')
     }
   }))
 )
 .add(
   'with red background',
   withNotes('Testing the background color for the editable area by setting it to red')(() => ({
     component: ContentEditableComponent,
     props: {
       styles: { 'background-color': 'red', 'color': '#fff', 'padding': '20px' },
       ngModel: 'The content goes here',
       ngModelChange: action('ngModelChange')
     }
   }))
 );

The first story renders the ContentEditable component with a yellow background. While the second renders the component with a red background.

Run the Storybook tool to view and test your stories by issuing the following CLI command:

npm run storybook

You should be able to see something similar to this:

Now that we are sure the Storybook stories are up and running, let’s set up Applitools to use these stories and run our visual automated tests.

Add and run Applitools Storybook SDK for Angular

To add Applitools Storybook SDK for Angular to this application issue the following CLI command:

npm install @applitools/eyes.storybook --save-dev

Make sure to grab an Applitool API Key and store it on your machine. For a complete tutorial on how to install and run Applitools Storybook SDK for Angular, you may check this link: Storybook Angular Tutorial.

To run the Storybook stories and send the snapshots to the Applitools Server, issue the following command:

npx [eyes-storybook](https://github.com/applitools/eyes.storybook)

The command simply opens the Storybook stories, runs them one by one, and then sends all the DOM snapshots to the Applitools Server. Let’s have a look at the test results inside Applitools Test Manager.

Review test results on Applitools Test Manager

We can see the results of the tests we just ran from the Applitools Test Manager. To access the Applitools Test Manager, navigate to https://www.applitools.com. Sign in to get onto the Dashboard. For a detailed look at the Applitools Test Manager, you can check my article on Applitools — The automated visual regression testing framework

The results for running the Storybook tests show the following:

The test manager lists the test runs or batches (as referred to by Applitools) on the left- hand side. Clicking on any of the batches displays all of the snapshots for all of the Storybook stories in your application.

Click on the first snapshot (the red color) to expand and review it in detail:

A rich toolbox is available to zoom in/out on the snapshot and compare this snapshot to any previously taken, known as the baseline. In this case, since this is the first time we are running the stories, there won’t be any baseline set. Therefore, Applitools Test Manager sets these snapshots as a baseline for upcoming regression test cycles.

Next, we’re going to simulate what happens when we have a visual regression in one of our components. To do this most easily, we’ll change one of our Storybook stories to render our component in a way that will be different from the baseline images we took earlier. Then, when we re-run the visual testing, we should see a discrepancy appear that we’ll have to resolve.

To do this, let’s assume that the story named in the red background above, has the ngModel value changed and now reads as follows:

.add(
  'with red background',
  withNotes('Testing the background color for the editable area by setting it to red')(() => ({
    component: ContentEditableComponent,
    props: {
      styles: { 'background-color': 'red', 'color': '#fff', 'padding': '20px' },
      ngModel: 'The red content goes here',
      ngModelChange: action('ngModelChange')
    }
  }))
 )

Now run this command:

npx eyes-storybook

The command gives you a detailed test result every time you run it. Check the following results:

Using @applitools/eyes.storybook version 2.1.9.

√ Storybook was started
√ Reading stories
√ Done 2 stories out of 2

[EYES: TEST RESULTS]:

ContentEditable Component: with yellow background [1024x768] — Passed

ContentEditable Component: with red background [1024x768] — Failed 1 of 1

A total of 1 difference was found.

See details at [https://eyes.applitools.com/app/test-results/00000251861893628194?accountId=D9XKRBVuYUmBxXpWWWsB3g~~](https://eyes.applitools.com/app/test-results/00000251861893628194?accountId=D9XKRBVuYUmBxXpWWWsB3g~~)

Total time: 36 seconds

Running the second story fails, as expected because we changed the content that was initially displayed inside the ContentEditable component. The test result output provides you with a link to check the discrepancies online. Click on the link to open the issues directly in the Applitools Test Manager:

A new batch is displayed on the left-hand side with a status of Unresolved. The Unresolved status indicates that the Applitools Test Manager discovered a discrepancy between the two test runs. This will require your input in order to resolve the discrepancy. Either approve the difference, and create a new baseline, or reject it to keep the original baseline.

Notice the blue square above indicating the Not Equal sign. This means the second snapshot test run has some differences to the first test run snapshot (the baseline). Clicking on the first snapshot reveals the differences between both snapshots. The current one and the baseline. The differences in content are highlighted in blue. You can also compare the new snapshot with the baseline by selecting both:

This should display both side by side and all differences are highlighted for you. You may spend more time at the Applitools Test Manager to explore all the rich features provided for you to do a thorough analysis on running the story tests.

Conclusion

This article touched the surface on how you can mix together Storybook and Angular together in one application. By means of Applitools Storybook SDK for Angular, you can provide automated visual UI testing by running the Storybook stories and generate snapshots that are then sent to the Applitools AI Server to compare and analyze and prepare the test results for you.

You can grab the code for this article by cloning the repository on GitHub.

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About the author(s)

Bilal Haidar
Author, Developer, and Mentor: Professional ASP.NET 3.5 Security, Membership, and Role Management with C# and VB | A Complete Guide to VueJS
@bhaidar @bhaidar

Exploring Angular Forms: A New Alternative with Signals

Exploring Angular Forms: A New Alternative with Signals In the world of Angular, forms are essential for user interaction, whether you're crafting a simple login page or a more complex user profile interface. Angular traditionally offers two primary approaches: template-driven forms and reactive forms. In my previous series on Angular Reactive Forms, I explored how to harness reactive forms' power to manage complex logic, create dynamic forms, and build custom form controls. A new tool for managing reactivity - signals - has been introduced in version 16 of Angular and has been the focus of Angular maintainers ever since, becoming stable with version 17. Signals allow you to handle state changes declaratively, offering an exciting alternative that combines the simplicity of template-driven forms with the robust reactivity of reactive forms. This article will examine how signals can add reactivity to both simple and complex forms in Angular. Recap: Angular Forms Approaches Before diving into the topic of enhancing template-driven forms with signals, let’s quickly recap Angular's traditional forms approaches: 1. Template-Driven Forms: Defined directly in the HTML template using directives like ngModel, these forms are easy to set up and are ideal for simple forms. However, they may not provide the fine-grained control required for more complex scenarios. Here's a minimal example of a template-driven form: ` ` 2. Reactive Forms: Managed programmatically in the component class using Angular's FormGroup, FormControl, and FormArray classes; reactive forms offer granular control over form state and validation. This approach is well-suited for complex forms, as my previous articles on Angular Reactive Forms discussed. And here's a minimal example of a reactive form: ` ` Introducing Signals as a New Way to Handle Form Reactivity With the release of Angular 16, signals have emerged as a new way to manage reactivity. Signals provide a declarative approach to state management, making your code more predictable and easier to understand. When applied to forms, signals can enhance the simplicity of template-driven forms while offering the reactivity and control typically associated with reactive forms. Let’s explore how signals can be used in both simple and complex form scenarios. Example 1: A Simple Template-Driven Form with Signals Consider a basic login form. Typically, this would be implemented using template-driven forms like this: ` ` This approach works well for simple forms, but by introducing signals, we can keep the simplicity while adding reactive capabilities: ` ` In this example, the form fields are defined as signals, allowing for reactive updates whenever the form state changes. The formValue signal provides a computed value that reflects the current state of the form. This approach offers a more declarative way to manage form state and reactivity, combining the simplicity of template-driven forms with the power of signals. You may be tempted to define the form directly as an object inside a signal. While such an approach may seem more concise, typing into the individual fields does not dispatch reactivity updates, which is usually a deal breaker. Here’s an example StackBlitz with a component suffering from such an issue: Therefore, if you'd like to react to changes in the form fields, it's better to define each field as a separate signal. By defining each form field as a separate signal, you ensure that changes to individual fields trigger reactivity updates correctly. Example 2: A Complex Form with Signals You may see little benefit in using signals for simple forms like the login form above, but they truly shine when handling more complex forms. Let's explore a more intricate scenario - a user profile form that includes fields like firstName, lastName, email, phoneNumbers, and address. The phoneNumbers field is dynamic, allowing users to add or remove phone numbers as needed. Here's how this form might be defined using signals: ` > Notice that the phoneNumbers field is defined as a signal of an array of signals. This structure allows us to track changes to individual phone numbers and update the form state reactively. The addPhoneNumber and removePhoneNumber methods update the phoneNumbers signal array, triggering reactivity updates in the form. ` > In the template, we use the phoneNumbers signal array to dynamically render the phone number input fields. The addPhoneNumber and removePhoneNumber methods allow users to reactively add or remove phone numbers, updating the form state. Notice the usage of the track function, which is necessary to ensure that the ngFor directive tracks changes to the phoneNumbers array correctly. Here's a StackBlitz demo of the complex form example for you to play around with: Validating Forms with Signals Validation is critical to any form, ensuring that user input meets the required criteria before submission. With signals, validation can be handled in a reactive and declarative manner. In the complex form example above, we've implemented a computed signal called formValid, which checks whether all fields meet specific validation criteria. The validation logic can easily be customized to accommodate different rules, such as checking for valid email formats or ensuring that all required fields are filled out. Using signals for validation allows you to create more maintainable and testable code, as the validation rules are clearly defined and react automatically to changes in form fields. It can even be abstracted into a separate utility to make it reusable across different forms. In the complex form example, the formValid signal ensures that all required fields are filled and validates the email and phone numbers format. This approach to validation is a bit simple and needs to be better connected to the actual form fields. While it will work for many use cases, in some cases, you might want to wait until explicit "signal forms" support is added to Angular. Tim Deschryver started implementing some abstractions around signal forms, including validation and wrote an article about it. Let's see if something like this will be added to Angular in the future. Why Use Signals in Angular Forms? The adoption of signals in Angular provides a powerful new way to manage form state and reactivity. Signals offer a flexible, declarative approach that can simplify complex form handling by combining the strengths of template-driven forms and reactive forms. Here are some key benefits of using signals in Angular forms: 1. Declarative State Management: Signals allow you to define form fields and computed values declaratively, making your code more predictable and easier to understand. 2. Reactivity: Signals provide reactive updates to form fields, ensuring that changes to the form state trigger reactivity updates automatically. 3. Granular Control: Signals allow you to define form fields at a granular level, enabling fine-grained control over form state and validation. 4. Dynamic Forms: Signals can be used to create dynamic forms with fields that can be added or removed dynamically, providing a flexible way to handle complex form scenarios. 5. Simplicity: Signals can offer a simpler, more concise way to manage form states than traditional reactive forms, making building and maintaining complex forms easier. Conclusion In my previous articles, we explored the powerful features of Angular reactive forms, from dynamic form construction to custom form controls. With the introduction of signals, Angular developers have a new tool that merges the simplicity of template-driven forms with the reactivity of reactive forms. While many use cases warrant Reactive Forms, signals provide a fresh, powerful alternative for managing form state in Angular applications requiring a more straightforward, declarative approach. As Angular continues to evolve, experimenting with these new features will help you build more maintainable, performant applications. Happy coding!...

Oct 4, 2024

5 mins

AngularJavaScript

SSR Finally a First-Class Citizen in Angular?

I am sure you've already heard about server-side rendering (SSR). Generally, it's a technique used to deliver the HTML content generated by the server to the client. The client-side JavaScript framework then hydrates that HTML content to provide a fully interactive application. SSR provides numerous benefits if used correctly, including improved initial load times, better content indexing by search engines, and improved performance on lower-tier devices. Driven by the need for faster, more efficient web applications, with the rise in popularity of Node.js and, thus, server-side JavaScript, SSR has become a de facto standard in modern web development frameworks. At first, SSR was being provided as a part of meta-frameworks like Next.js, Nuxt, or Analog.js. Then, React introduced React Server Components, which marked a significant milestone in the way we think about front-end development. We think of front-end frameworks as being effectively full-stack, and a purely SPA approach is falling out of favor. However, I'm willing to bet that if you're a developer focused mostly on Angular, you may not have heard as much about SSR as your React counterparts. For a long time, Angular has been mostly focused on the SPA approach, and while we had Angular Universal or Analog.js, it was not as widely adopted. And that makes sense, given that Angular was widely regarded as best suited for complex, interactive applications, such as SaaS products or internal company tools, where SEO and initial load times were not as critical as they are for consumer-facing applications. Nevertheless, we have been blessed with the so-called Angular Renaissance, which has, among other things, brought SSR to the forefront of Angular development with the @angular/ssr package. Let's look at what Angular SSR is, how it works, and how you can get started. @angular/ssr The @angular/ssr package is not new; it was written from scratch. It's still Angular Universal. However, it's been pulled into the Angular CLI repository, and the appropriate schematics have been added to make it easier to use. What that means is that you can now add SSR to your Angular application with a single command: ` and you can generate a new SSR application with: ` And to make SSR a first-class citizen, the Angular team is planning to make it the default in the next version. But surely, it's not only rebranding and some CLI commands, you may say. And you're right. You may remember that hydration in Angular Universal has not been optimal as it was destructive and required essentially a complete re-render of the application, thus pretty much negating the benefits of SSR. With the introduction of non-destructive hydration in Angular 16 and its stability in Angular 17, the Angular team has taken a significant step forward in making SSR a first-class citizen. How to Make an SSR-capable Angular Application Let's look at how to use Angular SSR in practice by creating a simple SSR app. First, we need to create a new Angular application with SSR support: ` That will generate a few server-specific files: - server.ts, which is an Express server configured to handle Angular SSR requests by default but can also be extended to handle API routes, or anything else that Express can handle. - src/app/app.config.server.ts provides configuration for the server application similar to your app.config.ts, which defines the configuration for your client application. Both export an instance of ApplicationConfig - src/main.server.ts bootstraps the server application in a similar way to what main.ts does for your client app by calling the bootstrapApplication function. You should have an SSR application ready just like that. You can verify that by running ng serve. The terminal output should show you information about the server bundles generated, and you should be able to see the default app when going to http://localhost:4200. Open the Developer Tools and check the console to see that hydration is enabled. You'll see a message with hydration-related stats, such as the number of components and nodes hydrated. Speaking of hydration... Client Hydration If you open the src/app/app.config.ts in your new SSR application, you'll notice one interesting provider: provideClientHydration(). This provider is crucial for enabling hydration - a process that restores the server-side rendered application on the client. Hydration improves application performance by avoiding extra work to re-create DOM nodes. Angular tries to match existing DOM elements to the application's structure at runtime and reuses DOM nodes when possible. This results in a performance improvement measured using Core Web Vitals statistics, such as reducing the Interaction To Next Paint (INP), Largest Contentful Paint (LCP), and Cumulative Layout Shift (CLS). Improving these metrics also positively impacts SEO performance. Without hydration enabled, server-side rendered Angular applications will destroy and re-render the application's DOM, which may result in visible UI flicker, negatively impact Core Web Vitals like LCP, and cause layout shifts. Enabling hydration allows the existing DOM to be reused and prevents flickering. Event Replay and Improved Debugging With Angular 18, event replay, a feature that significantly enhances the SSR experience, came into developer preview. Event replay captures user interactions during the SSR phase and replays them once the application is hydrated. This ensures that user actions, such as adding items to a cart, are not lost during the hydration process, providing a seamless user experience even on slow networks. To enable event replay, you can add withEventReplay to your provideClientHydration call: ` Furthermore, Angular 18 takes another step towards making SSR a first-class citizen by enhancing the debugging experience with Angular DevTools. Now, DevTools include overlays and detailed error breakdowns, empowering developers to visualize and troubleshoot hydration issues directly in the browser. Constraints However, hydration imposes a few constraints on your application that are not present without hydration enabled. Your application must have the same generated DOM structure on both the server and the client. The hydration process expects the DOM tree to have the same structure in both environments, including whitespaces and comment nodes produced during server-side rendering. Direct DOM Manipulation The fact that server and client DOM structures must match means that components that manipulate the DOM using native DOM APIs or use innerHTML or outerHTML will encounter hydration errors. The errors are thrown because Angular is unaware of these changes and cannot resolve them during hydration. Examples include accessing the document, querying for specific elements, and injecting additional nodes using appendChild. Detaching DOM nodes and moving them to other locations will also cause errors. Direct DOM manipulation is generally considered bad practice in Angular, so I recommend refactoring your components to avoid it regardless of hydration. However, in warranted cases where refactoring is not feasible, you can use the ngSkipHydration attribute until a hydration-friendly solution can be implemented. You can use it directly in a template: ` or as a host binding: ` > Note: The ngSkipHydration attribute forces Angular to skip hydrating the entire component and its children. So use this attribute carefully, as, for example, applying it to your root application component would effectively disable hydration for the entire application. Valid HTML Structure Another constraint is that invalid HTML structures in component templates can result in DOM mismatch errors during hydration. Common issues include: - without a - inside a - inside an - inside another Again, if you have an invalid HTML, you should fix this regardless of hydration. If you are unsure about your HTML's validity, you can use the W3 validator to check it. Zoneless apps or custom Zone.js Hydration relies on a signal from Zone.js when it becomes stable. Custom or "noop" Zone.js implementations may thus disrupt the timing of this event, triggering the serialization or cleanup process too early or too late. This configuration is not yet fully supported. While Zoneless is already available in developer preview and we could assume this issue will be resolved when it lands as stable, there is no explicit ETA mentioned in the official roadmap. I18n One of the biggest blockers for adoption of client hydration was the lack of support for internationalization with hydration. By default, Angular 17 skipped hydration for components that used i18n blocks, re-rendering them from scratch. In Angular 18, however, hydration for i18n blocks got into developer preview. To enable hydration for i18n blocks, you can add withI18nSupport to your provideClientHydration call. ` Third-Party Libraries with DOM Manipulation The last thing to consider is third-party libraries that manipulate DOM, such as D3 charts. They could cause DOM mismatch errors when hydration is enabled. You can use the ngSkipHydration attribute to skip hydration for components rendered using these libraries. Conclusion The Angular team has been doing great work to make the framework more modern and competitive, hearing the community feedback and adjusting the roadmap accordingly. And SSR is an excellent example of that. With the introduction of non-destructive hydration in Angular 16 and making it stable in Angular 17, the Angular team has taken a significant step forward in making SSR a first-class citizen in Angular. The @angular/ssr package is now part of the Angular CLI, making adding SSR to your Angular application easier. The Angular team plans to make SSR the default in the next version, further solidifying its position in the Angular ecosystem. However, as with any new feature, there are some constraints and best practices to follow when using SSR with Angular. You should be aware of hydration's limitations and ensure your application is compatible with it. However, if you follow the guidelines provided by the Angular team, you should be able to take advantage of the benefits of SSR without any significant issues....

Jun 26, 2024

8 mins

AngularJavaScriptExpress.js

Take your App to the Next Level with Vue 3

Vue 3 has now officially launched and you are probably wondering how you are going to start migrating your existing Vue 2 apps to Vue 3. I will be honest with you: a framework migration is always the most tedious and painstaking task you will ever encounter. The good news is that migrating from Vue 2 to Vue 3 is not that difficult and complicated. As you may know, Vue 3 source code has been written from scratch. However, the maintainers of the framework made sure not to change the API too much. In other words, we will benefit from all the goodies Vue 3 brings, with minimal change. How awesome is that?! Vue 3 Official Migration Guide The Vue documentation website has been refreshed to reflect the latest changes. The Vue community has maintained the best documentation to help us learn and use Vue. The Vue documentation dedicates a section on Vue 3 Migration making mention of the new features, the breaking changes for Vue 2 apps, the supporting libraries like Vue CLI, Vuex, Vue Router and others. The website explicitly states that the team is still working on a dedicated migration guide from Vue 2 to Vue 3. Meanwhile, until an official migration guide is released, let’s get a little insight on what could possibly be involved if you were to tackle this for yourself. What to consider before upgrading to Vue 3? As Vue 3 is still new, there will be some things to keep in mind. There are thousands of applications and third-party libraries created for Vue 2 and even Vue 1.5. It’s going to be a lengthy and time consuming effort to migrate all those libraries to support Vue 3. Before you attempt any migration process, make sure all the libraries you use are supported by Vue 3. For instance, Vuetify isn't. You can read more about this here. In addition, if you use any of the third-party libraries, they need to be checked or you might find they have upgraded already. Moreover, the Vue 3 reactivity system has been rewritten to utilize the new language features in ES2015. Vue 3 uses proxies for its reactivity system instead of the Object.defineProperty() function. JavaScript proxies are supported by most modern browsers. Unfortunately, Proxies cannot be polyfilled for older browsers; therefore, Vue 3 offers two implementations of it’s reactivity system. One implementation will use proxies for the most recent and modern browsers. The other one will fall back to the Vue 2 way of implementing reactivity to support the older browsers. Step by Step Migration - Demo In this section, we'll go through migrating the This Dot - Vue Meetup website. The existing website is built with Vue 2. It’s essential to follow the steps below as is. Of course, depending on the features you’ve used, you will adjust this workflow to fit your needs and migrate more features in your apps. Let's start! Step 1: Create a new Git branch It’s important to start off with a brand new branch to play around with the migration. This way your main branches, like master or dev, will remain intact without disrupting any live code. Let’s assume we are branching from the master branch. Run the following command to create a new branch: ` Step 2: Install the latest Vue CLI version Currently, as of the time of writing this article, the latest version of the Vue CLI is 4.5.6. To install the latest version, run the following command: ` Verify the installation by running the following command and making sure it reads as @vue/cli 4.5.6: ` Upgrading the Vue CLI not only helps in upgrading the existing application, but it also gives you the chance to scaffold a new Vue 3 app in the future. Step 3: Upgrade the Vue libraries The next step is to upgrade the Vue NPM packages and all other packages used inside the package.json file. To start with, open the package.json file and make sure to amend the Vue libraries with the following versions: ` Now, let’s upgrade the rest of the libraries using the Vue CLI. Run the following command to start upgrading the libraries: ` The command goes through all the libraries you are using inside the package.json file and tries to upgrade them to the latest compatible version. For example, when I run this command, the Vue CLI detects the Vue libraries that need to be upgraded and prompts for confirmation: Type Y to continue with the upgrade. In summary, the upgrade reported the following packages changes, additions, and removal. While the CLI is upgrading the @vue/cli-plugin-eslint it will also upgrade the current ESLint version installed on your computer. The latest Vue CLI supports ESLint v6. Once again, the Vue CLI prompts for confirmation before upgrading ESLint. Type Y to continue with the upgrade. ` The numbers will definitely be different for you and depending on the app. It’s now time to run the app and make sure you don’t have missing libraries or other problems. In my case, I ran the app and got a few ESLint issues. Luckily, the Vue CLI comes packaged with a command to auto fix ESLint issues. In this case, you run the npm run lint and the Vue CLI handles the rest for you! Step 4: Add the @vue/compiler-sfc NPM package The @vue/compiler-sfc package contains lower level utilities that you can use if you are writing a plugin / transform for a bundler or module system that compiles Vue single file components into JavaScript. It is used in the vue-loader. This is an essential component if you are using Single File Components which is the case in most of the Vue apps. Let’s install this package by running the following command: ` Let’s move on and start upgrading the source code to use the latest APIs offered by Vue 3. Step 5: Upgrade the main.js file Vue 3 changes the way an application is created by introducing the createApp() function. Back in Vue 2 and earlier versions, we used to create a global Vue instance. This approach had several disadvantages. The main one had third-party libraries to making changes to our Vue single App instance. By introducing createApp(), you can instantiate multiple Vue apps side by side. It creates a context or boundary for your app instance where you do all the registration as you will see shortly. Typically, a Vue app is started inside the main.js file. Let’s visit this file and make the necessary changes to upgrade to Vue 3. ` This is a slimmed down version of the original main.js file in the app. Let’s dissect the file one line at a time and upgrade accordingly. ` Replace the line above with: ` Let’s replace the code that’s creating the app using the Vue 3 createApp() function. ` Replace with: ` The app variable now holds a new Vue app instance for us. The router instance will be registered separately. Let’s update the Vue component registration. ` Replace with: ` With Vue 3, you register components at the app instance level and not globally. Let’s update the Vue mixin registration. ` Replace with: ` Now register the router on the app instance as follows: ` Now let’s register the vue-analytics plugin on the app instance. ` Replace with: ` The plugin is now installed on the app instance rather than the global Vue instance. This is also valid for any other plugin out there. Make sure to remove the line below as it’s not needed anymore in Vue 3 apps: ` Finally, let’s mount the app instance by using the following: ` The final version of the upgrade main.js file looks like this: ` That’s it! Step 6: Upgrade the router.js file The Vue Router has undergone changes and it’s now under v4.0. Let’s review what the current router.js file looks like: ` Replace the import statements with the following line: ` Instead of creating a new instance of the Router object, we will be using the new function provided by Vue Router which is createRouter(). ` The router.js file now exports an instance of the Router object using the createRoute() function. This function expects an input parameter of type object. The routes and history properties are the minimum accepted to pass into this object. The routes array is still the same as in Vue 2. It’s an array of routes, nothing has changed here. The createWebHashHistory() function is now used to specify a Hash History mode in the Vue Router. As a side note, depending on what you are using in your app, there is also the createWebHistory() function that sets the mode to HTML 5. You can read more about History Modes. Next, we will update the scrollBehavior() function as it has undergone some major changes. Replace the existing function with the following: ` You can read more about Scroll Behavior in the Vue Router 4.0. Now, let’s run the app and see if everything works as expected. When I run the app, I get the following warning in the Dev Tools: ` This warning has to do with Vue Router and the Transition component. You can read more about the Transitions in Vue Router. Let’s navigate to the App.vue component and check what the current source code is: ` In Vue Router v4.0, you can no longer nest a component inside a component. The fix is simple and provided to you in the documentation. Replace the above with the following: ` These were all the steps needed to upgrade the Vue Meetup app. Others I’d like to draw your attention to a few more things when upgrading your apps to Vue 3. One of the components in the app had a single slot; that is, the default slot. The way it was used in the Vue 2 app was: ` When I ran the app, the component was showing nothing, an empty screen! It seems Vue 2 was more tolerant by not forcing me to specify the name of the slot, even though this is the default slot. The quick fix in Vue 3 is as follows: ` Something else I didn’t mention is the Vuex v4.0. The same steps that we followed to upgrade the Vue Router can be followed here. The approach is similar. You can read more about the Vuex v4.0 Breaking Changes. Conclusion I am pretty sure we will all face more issues and encounter different hiccups while upgrading our apps. It will all depend on the features of your Vue 2. Remember, everything has a solution! While we wait for the Vue team to share an official migration guide, start trying to upgrade and see how you go. If you get stuck, feel free to drop me a message on twitter using my Twitter handle @bhaidar....

Sep 30, 2020

9 mins

Vue

“Music and code have a lot in common,” freeCodeCamp’s Jessica Wilkins on what the tech community is doing right to onboard new software engineers

Before she was a software developer at freeCodeCamp, Jessica Wilkins was a classically trained clarinetist performing across the country. Her days were filled with rehearsals, concerts, and teaching, and she hadn’t considered a tech career until the world changed in 2020. > “When the pandemic hit, most of my gigs were canceled,” she says. “I suddenly had time on my hands and an idea for a site I wanted to build.” That site, a tribute to Black musicians in classical and jazz music, turned into much more than a personal project. It opened the door to a whole new career where her creative instincts and curiosity could thrive just as much as they had in music. Now at freeCodeCamp, Jessica maintains and develops the very JavaScript curriculum that has helped her and millions of developers around the world. We spoke with Jessica about her advice for JavaScript learners, why musicians make great developers, and how inclusive communities are helping more women thrive in tech. Jessica’s Top 3 JavaScript Skill Picks for 2025 If you ask Jessica what it takes to succeed as a JavaScript developer in 2025, she won’t point you straight to the newest library or trend. Instead, she lists three skills that sound simple, but take real time to build: > “Learning how to ask questions and research when you get stuck. Learning how to read error messages. And having a strong foundation in the fundamentals” She says those skills don’t come from shortcuts or shiny tools. They come from building. > “Start with small projects and keep building,” she says. “Books like You Don’t Know JS help you understand the theory, but experience comes from writing and shipping code. You learn a lot by doing.” And don’t forget the people around you. > “Meetups and conferences are amazing,” she adds. “You’ll pick up things faster, get feedback, and make friends who are learning alongside you.” Why So Many Musicians End Up in Tech A musical past like Jessica’s isn’t unheard of in the JavaScript industry. In fact, she’s noticed a surprising number of musicians making the leap into software. > “I think it’s because music and code have a lot in common,” she says. “They both require creativity, pattern recognition, problem-solving… and you can really get into flow when you’re deep in either one.” That crossover between artistry and logic feels like home to people who’ve lived in both worlds. What the Tech Community Is Getting Right Jessica has seen both the challenges and the wins when it comes to supporting women in tech. > “There’s still a lot of toxicity in some corners,” she says. “But the communities that are doing it right—like Women Who Code, Women in Tech, and Virtual Coffee—create safe, supportive spaces to grow and share experiences.” She believes those spaces aren’t just helpful, but they’re essential. > “Having a network makes a huge difference, especially early in your career.” What’s Next for Jessica Wilkins? With a catalog of published articles, open-source projects under her belt, and a growing audience of devs following her journey, Jessica is just getting started. She’s still writing. Still mentoring. Still building. And still proving that creativity doesn’t stop at the orchestra pit—it just finds a new stage. Follow Jessica Wilkins on X and Linkedin to keep up with her work in tech, her musical roots, and whatever she’s building next. Sticker illustration by Jacob Ashley....

Apr 25, 2025

3 mins

JavaScriptSoftware Engineering

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Whether it's modernization or custom software solutions, our team of experts can guide you through best practices and how to build scalable, performant software that lasts.

Mixing Storybook with Angular with a Sprinkle of Applitools

Create Angular 7 App using the latest CLI

Create the ContentEditable Component

Add Storybook packages

Create and run a few Storybook stories

Add and run Applitools Storybook SDK for Angular

Review test results on Applitools Test Manager

Conclusion

Bilal Haidar

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