Angular

Truly Accessible Custom Components in Angular

Published Mar 25, 2020

Updated Feb 14, 2023

7 min read

Make it Accessible - 4 Part Series

This article was written over 18 months ago and may contain information that is out of date.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.

Truly Accessible Custom Components in Angular

For the first time in my "Make it Accessible" series, I'm going to work on building a component that meets the requirements specified in the WAI-ARIA Authoring Practices. We'll even do the optional stuff! When I was looking for a good example, I saw that most of the examples out there cover things like a radio button. I wanted to pursue this concept even further, so we're building an Accordion Component.

Exciting right? Let's do this!

Before we start, here you can access the source code of the accordion

The Problem

When we are building an Angular application, native HTML Elements can be used. And even though this is what I always recommend, there are cases that need something unique. An Accordion is not that unique, but it's certainly custom, and no native elements are required to build it.

The Solution

In this case, I'm going to stick to the specification instead of making all of the decisions myself. Instead, I'm going to the WAI-ARIA Authoring Practices, and will paste all we need to be compliant here.

I want to explicitly state that I'm not taking any credit for the specification.

1. Structure

An accordion is a vertically stacked set of interactive headings that each contain a title, content snippet, or thumbnail, representing a section of content. The headings function as controls that enable users to reveal or hide their associated sections of content. Accordions are commonly used to reduce the need to scroll when presenting multiple sections of content on a single page.

Terms for understanding accordions include:

1.1. Accordion Header

Label for our thumbnail, representing a section of content that also serves as a control for showing, and in some implementations, hiding the section of content.

1.2. Accordion Panel

Section of content associated with an accordion header.

In some accordions, there are additional elements that are always seen adjacent to the accordion header. For instance, a menu button may accompany each accordion header to provide access to actions that apply to that section. And, in some cases, a snippet of the hidden content may also be visually persistent.

2. Keyboard Interaction

2.1. Enter or Space

When focus is on the accordion header for a collapsed panel, expands the associated panel. If the implementation allows only one panel to be expanded, and if another panel is expanded, collapses that panel.
When focus is on the accordion header for an expanded panel, collapse the panel if the implementation supports collapsing. Some implementations require one panel to be expanded at all times, and allow only one panel to be expanded; so, they do not support a collapse function.

2.2. Tab

Moves focus to the next focusable element; all focusable elements in the accordion are included in the page Tab sequence.

2.3. Shift + Tab

Moves focus to the previous focusable element; all focusable elements in the accordion are included in the page Tab sequence.

2.4. Down Arrow (Optional):

If focus is on an accordion header, moves focus to the next accordion header. If focus is on the last accordion header, either does nothing or moves focus to the first accordion header.

2.5. Up Arrow (Optional):

If focus is on an accordion header, moves focus to the previous accordion header. If focus is on the first accordion header, either does nothing or moves focus to the last accordion header.

2.6. Home (Optional):

When focus is on an accordion header, moves focus to the first accordion header.

2.7. End (Optional):

When focus is on an accordion header, moves focus to the last accordion header.

3. WAI-ARIA Roles, States, and Properties

3.1. Accordion Header Title

The title of each accordion header is contained in an element with role button.

3.2. Level of Accordion Header

Each accordion header button is wrapped in an element with role heading that has a value set for aria-level that is appropriate for the information architecture of the page.

If the native host language has an element with an implicit heading and aria-level, such as an HTML heading tag, a native host language element may be used.
The button element is the only element inside the heading element. That is, if there are other visually persistent elements, they are not included inside the heading element.

3.3. Update aria-expanded accordingly

If the accordion panel associated with an accordion header is visible, the header button element has aria-expanded set to true. If the panel is not visible, aria-expanded is set to false.

3.4. Use aria-control respectively

The accordion header button element has aria-controls set to the ID of the element containing the accordion panel content.

3.5. Update aria-disabled accordingly

If the accordion panel associated with an accordion header is visible, and if the accordion does not permit the panel to be collapsed, the header button element has aria-disabled set to true.

3.6. Usage of aria regions

Optionally, each element that serves as a container for panel content has role region and aria-labelledby with a value that refers to the button that controls display of the panel.

Avoid using the region role in circumstances that create landmark region proliferation, e.g., in an accordion that contains more than approximately 6 panels that can be expanded at the same time.
Role region is especially helpful for the perception of structure by screen reader users when panels contain heading elements or a nested accordion.

Implementation

If you want to code along the way, I created a repository that has a branch with a starter accordion. Clone that repository, and let's do this together.

You dont have to care about the structure, the code I just gave you already has that. Our focus will be in the Keyboard Interactions, and the WAI-ARIA Roles, States, and Properties.

2. Keyboard Interactions

2.1. Enter or Space

I decided to allow users to collapse an expanded panel, so there's only one thing to do. We need to call the toggle method when clicking a header, with Enter or Space, when focused. Thankfully I decided to use a native HTML button, which comes out of the box with keyboard support.

2.2. Tab

The Tab funcionality comes out of the box too, as long as we make items tabbable. Since the headers are buttons, that's already true. One thing to keep in mind is that a panel's content shouldnt be tabbable when collapsed, but if you read 5 Tips to Make your Angular Apps more Accessible you will know that the ngIf directive removes the all of the content so we don't have to do anything else.

2.3. Shift + Tab

The same logic for 2.2 applies here.

The other interactions

We are getting closer to the fun stuff.

We'll need to listen to keyup events, if the pressed key is equal to any of the ones, required by WAI-ARIA, that we will act upon. Basically we need a keyup handler, a goToNext and goToPrevious methods. Let's jump on the code and do that:

Go to src/app.component.ts and do this:

// ...
const ARROW_DOWN = 'ArrowDown';
const ARROW_UP = 'ArrowUp';
const HOME = 'Home';
const END = 'End';

@Component(/*  */)
export class AppComponent implements AfterViewInit {
  // ...
  @ViewChildren(AccordionHeaderComponent) accordionHeaders: QueryList<
    ElementRef
  >;
  private panelQuantity: number;

  ngAfterViewInit() {
    this.panelQuantity = this.accordionHeaders.length;
  }

  private goToNext() {
    this.currentlyFocused = (this.currentlyFocused + 1) % this.panelQuantity;
  }

  private goToPrevious() {
    if (this.currentlyFocused === 0) {
      this.currentlyFocused = this.panelQuantity - 1;
    } else {
      this.currentlyFocused = this.currentlyFocused - 1;
    }
  }

  // ...

  handleKeyUp(event: KeyboardEvent) {
    switch (event.key) {
      case ARROW_DOWN:
        this.goToNext();
        break;
      case ARROW_UP:
        this.goToPrevious();
        break;
      case HOME:
        this.currentlyFocused = 0;
        return;
      case END:
        this.currentlyFocused = this.panelQuantity - 1;
        return;
      default:
        break;
    }
  }
}

Let's break it down. We are using the AfterViewInit hook to get the number of headers the accordion has. This will be useful for the Arrow support. That way, if the user presses the Up Arrow in the first item, the focus is sent to the last header, and the opposite for Down Arrow. Home and End are way easier, since the currentlyFocused is the mechanism we are using in order to know which one is currently focused in an imperative way, we just need to update it to first or the last, respectively.

Just to recap, we have successfully integrated keyboard support to our custom widget following WAI-ARIA spec.

3. WAI-ARIA Roles, States, and Properties

Now it's time to go a little deeper, and work with aria-* attributes, roles and properties.

I don't know how many times I've said this, but I'll keep saying it. If you think about accessibility from the design stage, you will dramatically reduce longterm development costs. Since I read the specs before starting, I made a few decisions in the starter code, so the two first things in the aria part are already done; the headers are buttons, and they contain a heading with a level.

3.3. Update aria-expanded accordingly

This one is extremely simple, since we already have the isOpen category in the AccordionHeader component, we just need to wire its value to the aria-expanded property in the button element. For this, you have to go to src/app/shared/components/accordion-header/accordion-header.component.html

<h2 class="header" [ngClass]="{ 'is-open': isOpen }">
  <button ... [attr.aria-expanded]="isOpen">
    <!-- ... -->
  </button>
</h2>

<!-- ... -->

3.4. Use aria-control respectively

This one is a bit trickier because we need a way to wire the button with the panel. For this, we'll need to use the index input property. With it, we'll assign a unique id to the panel, and will use the same value for the aria-controls. For this, you have to go to src/app/shared/components/accordion-header/accordion-header.component.html

<h2 class="header" [ngClass]="{ 'is-open': isOpen }">
  <button ... [attr.aria-controls]="'panel-' + index">
    <!-- ... -->
  </button>
</h2>

<div [id]="'panel-' + index">
  <!-- ... -->
</div>

In this case, we dont care about updating the aria-disabled property, because I decided to allow users to collapse expanded panels.

3.6. Usage of aria regions

This one is easier, but is also easy to forget. Right now, the panel is not a region. Without it, the panels are just containers for html, but they do not provide any extra information to Screen Reader users. That's why this is such an important step. For this, you have to go to src/app/shared/components/accordion-header/accordion-header.component.html

<!-- ... -->
<div ... [attr.aria-labelledby]="'accordion-' + index" role="region">
  <!-- ... -->
</div>

That's it!

The accordion header template will end up looking like this:

<h2 class="header" [ngClass]="{ 'is-open': isOpen }">
  <button
    [id]="'accordion-' + index"
    class="header__trigger"
    [appFocusable]="isFocused"
    (click)="togglePanel()"
    (focus)="setFocus()"
    (blur)="setBlur()"
    [attr.aria-expanded]="isOpen"
    [attr.aria-controls]="'panel-' + index"
  >
    <div class="header__title">
      <span>{{ headerTitle }}</span>
      <fa-icon [icon]="faAngleUp"></fa-icon>
    </div>
  </button>
</h2>

<div
  [id]="'panel-' + index"
  [attr.aria-labelledby]="'accordion-' + index"
  role="region"
>
  <ng-content *ngIf="isOpen"></ng-content>
</div>

Conclusion

I know this one was a little longer than the usual Make it Accessible articles, but it had to be done. We definitely needed to go into detail, and build a custom component that was totally compliant with the specs. Just as a reminder, make sure you have unique ids. Even though what I just gave you isn't reusable (we are not building an open source library), it can definitely give you more understanding of how to do this on your own.

In my free time, I'm currently working on building a small library that includes all the concepts I dive into in this series. If you would like to help me, feel free to drop a comment, or message me on Twitter.

This Dot is a consultancy dedicated to guiding companies through their modernization and digital transformation journeys. Specializing in replatforming, modernizing, and launching new initiatives, we stand out by taking true ownership of your engineering projects.

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Introduction to Zod for Data Validation

As web developers, we're often working with data from external sources like APIs we don't control or user inputs submitted to our backends. We can't always rely on this data to take the form we expect, and we can encounter unexpected errors when it deviates from expectations. But with the Zod library, we can define what our data ought to look like and parse the incoming data against those defined schemas. This lets us work with that data confidently, or to quickly throw an error when it isn't correct. Why use Zod? TypeScript is great for letting us define the shape of our data in our code. It helps us write more correct code the first time around by warning us if we are doing something we shouldn't. But TypeScript can't do everything for us. For example, we can define a variable as a string or a number, but we can't say "a string that starts with user_id_ and is 20 characters long" or "an integer between 1 and 5". There are limits to how much TypeScript can narrow down our data for us. Also, TypeScript is a tool for us developers. When we compile our code, our types are not available to the vanilla JavaScript. JavaScript can't validate that the data we actually use in our code matches what we thought we'd get when we wrote our TypeScript types unless you're willing to manually write code to perform those checks. This is where we can reach for a tool like Zod. With Zod, we can write data schemas. These schemas, in the simplest scenarios, look very much like TypeScript types. But we can do more with Zod than we can with TypeScript alone. Zod schemas let us create additional rules for data parsing and validation. A 20-character string that starts with user_id_? It's z.string().startsWith('user_id_').length(20). An integer between 1 and 5 inclusive? It's z.number().int().gte(1).lte(5). Zod's primitives give us many extra functions to be more specific about *exactly* what data we expect. Unlike TypeScript, Zod schemas aren't removed on compilation to JavaScript—we still have access to them! If our app receives some data, we can verify that it matches the expected shape by passing it to your Zod schema's parse function. You'll either get back your data in exactly the shape you defined in your schema, or Zod will give you an error to tell you what was wrong. Zod schemas aren't a replacement for TypeScript; rather, they are an excellent complement. Once we've defined our Zod schema, it's simple to derive a TypeScript type from it and to use that type as we normally would. But when we really need to be sure our data conforms to the schema, we can always parse the data with our schema for that extra confidence. Defining Data Schemas Zod schemas are the variables that define our expectations for the shape of our data, validate those expectations, and transform the data if necessary to match our desired shape. It's easy to start with simple schemas, and to add complexity as required. Zod provides different functions that represent data structures and related validation options, which can be combined to create larger schemas. In many cases, you'll probably be building a schema for a data object with properties of some primitive type. For example, here's a schema that would validate a JavaScript object representing an order for a pizza: ` Zod provides a number of primitives for defining schemas that line up with JavaScript primitives: string, number, bigint, boolean, date, symbol, undefined, and null. It also includes primitives void, any, unknown, and never for additional typing information. In addition to basic primitives, Zod can define object, array, and other native data structure schemas, as well as schemas for data structures not natively part of JavaScript like tuple and enum. The documentation contains considerable detail on the available data structures and how to use them. Parsing and Validating Data with Schemas With Zod schemas, you're not only telling your program what data should look like; you're also creating the tools to easily verify that the incoming data matches the schema definitions. This is where Zod really shines, as it greatly simplifies the process of validating data like user inputs or third party API responses. Let's say you're writing a website form to register new users. At a minimum, you'll need to make sure the new user's email address is a valid email address. For a password, we'll ask for something at least 8 characters long and including one letter, one number, and one special character. (Yes, this is not really the best way to write strong passwords; but for the sake of showing off how Zod works, we're going with it.) We'll also ask the user to confirm their password by typing it twice. First, let's create a Zod schema to model these inputs: ` So far, this schema is pretty basic. It's only making sure that whatever the user types as an email is an email, and it's checking that the password is at least 8 characters long. But it is *not* checking if password and confirmPassword match, nor checking for the complexity requirements. Let's enhance our schema to fix that! ` By adding refine with a custom validation function, we have been able to verify that the passwords match. If they don't, parsing will give us an error to let us know that the data was invalid. We can also chain refine functions to add checks for our password complexity rules: ` Here we've chained multiple refine functions. You could alternatively use superRefine, which gives you even more fine grained control. Now that we've built out our schema and added refinements for extra validation, we can parse some user inputs. Let's see two test cases: one that's bound to fail, and one that will succeed. ` There are two main ways we can use our schema to validate our data: parse and safeParse. The main difference is that parse will throw an error if validation fails, while safeParse will return an object with a success property of either true or false, and either a data property with your parsed data or an error property with the details of a ZodError explaining why the parsing failed. In the case of our example data, userInput2 will parse just fine and return the data for you to use. But userInput1 will create a ZodError listing all of the ways it has failed validation. ` ` We can use these error messages to communicate to the user how they need to fix their form inputs if validation fails. Each error in the list describes the validation failure and gives us a human readable message to go with it. You'll notice that the validation errors for checking for a valid email and for checking password length have a lot of details, but we've got three items at the end of the error list that don't really tell us anything useful: just a custom error of Invalid input. The first is from our refine checking if the passwords match, and the second two are from our refine functions checking for password complexity (numbers and special characters). Let's modify our refine functions so that these errors are useful! We'll add our own error parameters to customize the message we get back and the path to the data that failed validation. ` Now, our error messages from failures in refine are informative! You can figure out which form fields aren't validating from the path, and then display the messages next to form fields to let the user know how to remedy the error. ` By giving our refine checks a custom path and message, we can make better use of the returned errors. In this case, we can highlight specific problem form fields for the user and give them the message about what is wrong. Integrating with TypeScript Integrating Zod with TypeScript is very easy. Using z.infer<typeof YourSchema> will allow you to avoid writing extra TypeScript types that merely reflect the intent of your Zod schemas. You can create a type from any Zod schema like so: ` Using a TypeScript type derived from a Zod schema does *not* give you any extra level of data validation at the type level beyond what TypeScript is capable of. If you create a type from z.string.min(3).max(20), the TypeScript type will still just be string. And when compiled to JavaScript, even that will be gone! That's why you still need to use parse/safeParse on incoming data to validate it before proceeding as if it really does match your requirements. A common pattern with inferring types from Zod schemas is to use the same name for both. Because the schema is a variable, there's no name conflict if the type uses the same name. However, I find that this can lead to confusing situations when trying to import one or the other—my personal preference is to name the Zod schema with Schema at the end to make it clear which is which. Conclusion Zod is an excellent tool for easily and confidently asserting that the data you're working with is exactly the sort of data you were expecting. It gives us the ability to assert at runtime that we've got what we wanted, and allows us to then craft strategies to handle what happens if that data is wrong. Combined with the ability to infer TypeScript types from Zod schemas, it lets us write and run more reliable code with greater confidence....

Nov 15, 2024

7 mins

JavaScriptZod

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

The HTML Dialog Element: Enhancing Accessibility and Ease of Use

The HTML Dialog Element: Enhancing Accessibility and Ease of Use Dialogs are a common component added to applications, whether on the web or in native applications. Traditionally there has not been a standard way of implementing these on the web, resulting in many ad-hoc implementations that don’t act consistently across different web applications. Often, commonly expected features are missing from dialogs due to the complexity of implementing them. However, web browsers now offer a standard dialog element. Why use the dialog element? The native dialog element streamlines the implementation of dialogs, modals, and other kinds of non-modal dialogs. It does this by implementing many of the features needed by dialogs for you that are already baked into the browser. This is helpful as it reduces the burden on the developer when making their applications accessible by ensuring that user expectations concerning interaction are met, and it can also potentially simplify the implementation of dialogs in general. Basic usage Adding a dialog using the new tag can be achieved with just a few lines of code. ` However, adding the dialog alone won’t do anything to the page. It will show up only once you call the .showModal() method against it. ` Then if you want to close it you can call the .close() method on the dialog, or press the escape key to close it, just like most other modals work. Also, note how a backdrop appears that darkens the rest of the page and prevents you from interacting with it. Neat! Accessibility and focus management Correctly handling focus is important when making your web applications accessible to all users. Typically you have to move the current focus to the active dialog when showing them, but with the dialog element that’s done for you. By default, the focus will be set on the first focusable element in the dialog. You can optionally change which element receives focus first by setting the autofocus attribute on the element you want the focus to start on, as seen in the previous example where that attribute was added to the close element. Using the .showModal() method to open the dialog also implicitly adds the dialog ARIA role to the dialog element. This helps screen readers understand that a modal has appeared and the screen so it can act accordingly. Adding forms to dialogs Forms can also be added to dialogs, and there’s even a special method value for them. If you add a element with the method set to dialog then the form will have some different behaviors that differ from the standard get and post form methods. First off, no external HTTP request will be made with this new method. What will happen instead is that when the form gets submitted, the returnValue property on the form element will be set to the value of the submit button in the form. So given this example form: ` The form element with the example-form id will have its returnValue set to Submit. In addition to that, the dialog will close immediately after the submit event is done being handled, though not before automatic form validation is done. If this fails then the invalid event will be emitted. You may have already noticed one caveat to all of this. You might not want the form to close automatically when the submit handler is done running. If you perform an asynchronous request with an API or server you may want to wait for a response and show any errors that occur before dismissing the dialog. In this case, you can call event.preventDefault() in the submit event listener like so: ` Once your desired response comes back from the server, you can close it manually by using the .close() method on the dialog. Enhancing the backdrop The backdrop behind the dialog is a mostly translucent gray background by default. However, that backdrop is fully customizable using the ::backdrop pseudo-element. With it, you can set a background-color to any value you want, including gradients, images, etc. You may also want to make clicking the backdrop dismiss the modal, as this is a commonly implemented feature of them. By default, the <dialog> element doesn’t do this for us. There are a couple of changes that we can make to the dialog to get this working. First, an event listener is needed so that we know when the user clicks away from the dialog. ` Alone this event listener looks strange. It appears to dismiss the dialog whenever the dialog is clicked, not the backdrop. That’s the opposite of what we want to do. Unfortunately, you cannot listen for a click event on the backdrop as it is considered to be part of the dialog itself. Adding this event listener by itself will effectively make clicking anywhere on the page dismiss the dialog. To correct for this we need to wrap the contents of the dialog content with another element that will effectively mask the dialog and receive the click instead. A simple element can do! ` Even this isn’t perfect though as the contents of the div may have elements with margins in them that will push the div down, resulting in clicks close to the edges of the dialog to dismiss it. This can be resolved by adding a couple of styles the the wrapping div that will make the margin stay contained within the wrapper element. The dialog element itself also has some default padding that will exacerbate this issue. ` The wrapping div can be made into an inline-block element to contain the margin, and by moving the padding from the parent dialog to the wrapper, clicks made in the padded portions of the dialog will now interact with the wrapper element instead ensuring it won’t be dismissed. Conclusion Using the dialog element offers significant advantages for creating dialogs and modals by simplifying implementation with reasonable default behavior, enhancing accessibility for users that need assistive technologies such as screen readers by using automatic ARIA role assignment, tailored support for form elements, and flexible styling options....

Oct 25, 2024

4 mins

HTMLJavaScript

Understanding the Difference Between `:focus` and `:focus-visible` in CSS

Understanding the Difference Between :focus and :focus-visible in CSS I have learned my fair share about the importance of keyboard accessibility, so I know that visual indication of the focused element is very important. But the well-known :focus pseudo-class is not always the best fit for this job. That's where :focus-visible comes in. Let's look at the differences between these two pseudo-classes and explore the best practices for using them effectively. What is the :focus Pseudo-Class? The :focus pseudo-class is a CSS selector that applies styles to any element that receives focus, regardless of how that focus was triggered. This includes focus events from keyboard navigation, mouse clicks, and touch interactions. Example Usage of :focus ` In this example, the button will display a blue outline whenever it is focused, whether the user clicks on it with a mouse, taps it on a touchscreen, or navigates to it using the keyboard. What is the :focus-visible Pseudo-Class? The :focus-visible pseudo-class is more specialized. It only applies styles to an element when the browser determines that the focus should be visible. This typically occurs when the user navigates via the keyboard or assistive technologies rather than through mouse or touch input. Example Usage of :focus-visible ` Here, the button will only show a blue outline when focused through keyboard navigation or another input method that usually requires visible focus indicators. Key Differences Between :focus and :focus-visible :focus - Behavior: Applies to any element that receives focus, regardless of the input method. - Use Cases: Ensures that all interactions with the element are visually indicated, whether by mouse, keyboard, or touch. :focus-visible - Behavior: Applies styles only when the focus should be visible, such as using a keyboard or assistive technology. - Use Cases: Ideal for scenarios where you want to provide focus indicators only to keyboard and assistive technology users while avoiding unnecessary outlines for mouse and touch users, typically required by design. Accessibility Implications :focus - Pros: - Guarantees that all users can see when an element is focused, which is critical for accessibility. - Cons: - Can lead to a suboptimal experience for mouse users, as focus styles may appear unnecessarily during mouse interactions. :focus-visible - Pros: - Enhances user experience by showing focus indicators only when necessary, thus keeping the interface clean for mouse and touch users. - Tailors the experience for keyboard and assistive technology users, providing them with clear visual cues. - Cons: - Additional considerations may be required to ensure that focus indicators are not accidentally omitted, especially in older browsers that do not support :focus-visible. - There may be cases where you want to show focus indicators for all users, regardless of input method. Best Practices for Using :focus and :focus-visible To achieve the best accessibility and user experience, combining both :focus and :focus-visible in your CSS is often a good idea. Combining :focus and :focus-visible ` Here is a Stackblitz example of what such styling could look like for you to try out and play with. Additional Tips - Test with Keyboard and Assistive Technology: Ensure that your web application is navigable using a keyboard (Tab, Shift + Tab, etc.) and that focus indicators are visible for those who rely on them. It's never a bad idea to include accessibility testing in your e2e testing suite. - Provide Clear Focus Indicators: Make sure that focus indicators are prominent and easy to see. A subtle or hard-to-spot focus indicator can severely impact accessibility for users who rely on keyboard navigation. Conclusion The :focus-visible pseudo-class offers a more refined way to manage focus indicators, improving accessibility and user experience, particularly for keyboard and assistive technology users. By understanding the differences between :focus and :focus-visible, and applying best practices in your CSS, you can create more accessible and user-friendly web applications. Remember, accessibility should never be an afterthought. By thoughtfully applying focus styles, you ensure that all users, regardless of how they interact with your site, can easily navigate and interact....

Nov 8, 2024

3 mins

AccessibilityCSSPlaywright

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