required attribute is not supported for validation

Phenomenon

When marking a contenteditable container as required, the browser’s form validation engine does not check its content. Users can submit an empty editor even if it’s logically “mandatory”.

Reproduction Steps

1. Create a <form>.
2. Add <div contenteditable="true" required></div>.
3. Add a submit button.
4. Leave the div empty and click submit.
5. Observe that the form submits without showing a “Please fill out this field” tooltip.

Expected Behavior

The browser should ideally support native validation for editable regions or provide a focused pseudo-class for validation states.

Solution

Use a hidden input with the required attribute and sync its value, or use the checkValidity() API manually on form submission.