The setCustomValidity() method of the HTMLButtonElement interface sets the custom validity message for the <button> element. Use the empty string to indicate that the element does not have a custom validity error.
setCustomValidity(string)stringThe string containing the error message. The empty string removes any custom validity errors.
None (undefined).
const errorButton = document.getElementById("checkErrors");
const errors = issuesToReport();
if (errors) {
errorButton.setCustomValidity("There is an error");
} else {
errorButton.setCustomValidity("");
}