The clear algorithm does not work for input elements in Range or Color state

[JohnChen0]

In chapter 14. Element Interaction:

set the value of the element to an empty string

The clear algorithm for input elements requires setting the value of the element to an empty string. However, this is not possible for input elements in Range or Color state. Both https://html.spec.whatwg.org/#range-state-(type=range) and https://html.spec.whatwg.org/#color-state-(type=color) specify that "User agents must not allow the user to set the value to the empty string."

For an input element in Range state, the clear algorithm should set its value to the default value, as given in the HTML spec. For input elements in Color state, the clear algorithm should set its value to "#000000".

[andreastt]

HTML differentiates between a form control’s internal value, the value content attribute, and the value IDL attribute. These are three different concepts.

In this case WebDriver conflates the notion of value, but it actually means the IDL attribute. Setting the IDL attribute to an empty string will cause the constraint validation to set the internal value to the default value.

It would probably be wiser as you suggest to special-case <input type=color> and <input type=range> to use the default value.

[JohnChen0]

Thanks for the clarification. It would be easier for people reading the standard if this is clarified in the standard itself.

[andreastt]

Related change to the clear algorithm for <input> elements:
#1317