Make sure that error and alert messages are accessible to screen reader users.
Do not rely on color alone to convey the error or alert message when something is not completed correctly or missing.
Provide a description and the nature of the error message and how to correct it. Example: “Please provide the correct date of birth. The primary applicant must be 18 years of age or older”.
Provide inline error messages to let the user know right away when a form element has not been completed or filled out correctly (when form control loses keyboard focus).
Make inline error messages accessible to screen reader users by adding ARIA labels.
Most screen reader and browser combinations announce a form control as “required” when using the required attribute.
Prevent screen readers from announcing required form controls as invalid by default, by using aria-invalid="false".
Update the aria-invalid attribute to “true” if the current value (or lack of value) of a required control does not pass validation.
Wait to declare form controls as invalid and display inline error messages once the control has lost focus, or there has been an adequate delay in key presses (a few seconds)
Use aria-describedby on required form controls to point to an element that will contain any necessary inline error messaging.
Can’t always rely on browser’s client-side error validation to be accessible.
Create a custom client-side validation script and helpful messaging by suppressing the browser’s default validation message by adding the novalidate attribute to the form element.
Default Error Message Treatment
<form novalidate> <label for="name"> Name:</label> <input id="name" hrequired aria-invalid="false"> </form> |
Invalid Error Message Treatment
<form novalidate> <label for="name"> Name:</label> <input id="name" required aria-describedby="name_msg" aria-invalid="true"> <span id="name_msg">Please enter your name.</span> </form> <form novalidate> <label for="Email"> Email:</label> <input id="Email" required aria-describedby="emal_msg" aria-invalid="true"> <span id="email_msg">The email address entered is invalid.</span> </form> |
https://codepen.io/TPG/pen/3b68c22db120c0960503fe892bb2c068
Wait to declare form controls as invalid until the form control has lost focus, or there has been an adequate delay in key presses (maybe a few seconds).
Example Default State:
<form novalidate>
<label for="name"> Name:</label>
<input id="name" required aria-invalid="false">
</form>
Example Invalid Error Message State:
<form novalidate>
<label for="name"> Name:</label>
<input id="name" required aria-describedby="name_msg" aria-invalid="true">
<span id="name_msg">Please enter your name.</span>
</form>
Code Example: https://codepen.io/TPG/pen/3b68c22db120c0960503fe892bb2c068