setValidity
fun setValidity(flags: ValidityStateFlags = definedExternally, message: String = definedExternally, anchor: HTMLElement = definedExternally)(source)
Marks internals's target element as suffering from the constraints indicated by the flags argument, and sets the element's validation message to message. If anchor is specified, the user agent might use it to indicate problems with the constraints of internals's target element when the form owner is validated interactively or reportValidity() is called.