Structuring accessible forms

On 28 September 2021, I was a guest on Ben Myer’s Twitch stream where we demonstrated best practices for accessible forms. Following is the example code and an explanation of what we covered.

See the Pen Accessible Forms by Rachele (@racheleditullio) on CodePen.

Creating our form fields

The two basic parts of a form field are its <label> and <input> elements. We semantically link the two by

  • Using the <label for="uniqueID"> attribute which matches the <input id="uniqueID"> attribute; or
  • Making the <input> element a child of the <label> element

Doing so allows screens readers to announce the field’s <label> when the <input> gets focus. It also enables the <label> as an additional hit area when using the mouse to focus on an <input>, which is especially useful for checkboxes and radio buttons.

We also need to specify the type of input using the <input type=""> attribute. Putting those together, we have a basic form with one text field and two radio buttons.

<form>
  <label for="name">Cat's name</label>
  <input type="text" id="name" name="name">

  <label><input type="radio" id="yes"> Yes</label>
  <label><input type="radio" id="no"> No</label>

  <button type="submit">Send</button>
</form>

A note on combo boxes

As much as possible, use native HTML <select> and <option> elements to create an expandable list of single-select options.

...
<label for="markings">Cat's markings</label>
<select name="markings" id="markings">
  <option value=""> select an option </option>
  <option value="solid">Solid</option>
  <option value="bi">Bi-color</option>
  ...
</select>
...

Grouping similar fields

Our radio buttons are labeled ‘yes’ and ‘no,’ but what are they for? We need to use the <fieldset> and <legend> elements to provide that semantic meaning. The <fieldset> groups the related form fields while the <legend> provides a name for the grouping. These are most often used for checkboxes and radio buttons but they can be useful for grouping other related fields, e.g. Shipping address.

Since radio button options may have similar names, group like radio buttons with the name="groupName" attribute. Keyboard users move between radio buttons in a group with the arrow keys.

...
<fieldset>
  <legend>Is your cat altered?</legend>
    <label><input type="radio" name="altered" id="yes"> Yes</label>
    <label><input type="radio" name="altered" id="no"> No</label>
</fieldset>
...

Marking required fields

Let’s create a required field for collecting email address with <input type="email">. Provide a visible indication of the required field for sighted users, such as an asterisk, but hide it from assistive technology using the aria-hidden="true" attribute.

Then there are two attributes we can use to programmatically define required fields: aria-required="true" and required.

Use one (not both) of these attributes to ensure required fields are conveyed appropriately to assistive technology. Screen readers will say required when announcing the form field name, role and state.

...
<label for="email">Your email<span aria-hidden="true">*</span></label>
<input type="email" id="email" name="email" aria-required="true">
...

The required attribute provides a first layer of form validation on submit. Many modern browsers will not submit a form with empty required fields and will even provide a visible error message.

a requried field in a web form that is empty and displays the message please fill out this form field.
Required field in Firefox for Windows

However, user agent error handling is not dependable as these error messages are not always announced or available to assistive technology; they can’t be styled or resized; and they are not persistent.

Handling errors

It’s important to provide a list of all errors at the top of the form or provide them in-context of the field in error. We can programmatically link the error message with the form field using the aria-describedby attribute.

...
<input type="email" id="email" name="email" aria-required="true" aria-describedby="error-email">
<p id="error-email">Email format email@domain.com</p>
...

When assistive technology users focus on the email field, the error message is announced along with the name, role and state of the field.

Verifying data

In addition to marking fields as required for assistive technology, we also have to indicate if the data entered into each field is valid. All required fields should also include the aria-invalid="true" attribute. Update this to “false” when it passes validation.

It’s also an accessibility requirement to make entering valid data as easy as possible. HTML has a set of autocomplete values that we need to use for any fields collecting personal information that might already be stored in the user’s browser. Email is one of these fields.

...
<input type="email" id="email" name="email" aria-required="true" aria-describedby="error-email" aria-invalid="true" autocomplete="email">
...

We can further enforce data validation in HTML for fields that aren’t necessarily required by using the pattern attribute that accepts a regular expression. Let’s create a field for collecting birthday with a required format of mm/dd/yyyy.

...
<input type="text" id="birthday" name="birthday" aria-describedby="help1" pattern="^\s*(1[012]|0?[1-9])\/(3[01]|[12][0-9]|0?[1-9])\/((?:19|20)\d{2})\s*$">
<p id="help1">Birthday format mm/dd/yyyy</p>
...

This pattern matching prevents the form from submitting if the data entered does not match the specified pattern.

Conclusion

I hope you found something to make your forms more accessible. I like forms because they have such a strong semantic structure. There are a lot of things to get right but it’s pretty straightforward what “right” means in this context: Make sure anything that is conveyed visually is also conveyed to assistive technology, including the states of form fields.

Semantic HTML stickers are here

I’m about to start public speaking at conferences and I wanted to design something I could give away. A sticker seemed like just the thing.

a color sticker about 2 inches wide cover a laptop logo. It says semantic HTML.

Feel free to DM me on Twitter with your address if you want one. Otherwise, I’m making the artwork available so you can print your own for non-commercial use.

Creative Commons license Download the semantic HTML sticker artwork

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