HTMLOutputElement: validity property
The validity read-only property of the HTMLOutputElement interface returns a ValidityState object that represents the validity states this element is in. Although <output> elements are never candidates for constraint validation, the validity state may still be invalid if a custom validity message has been set.
Value
A ValidityState object.
Examples
The following example demonstrates that an <output> is in an invalid state when a customError is set; in this state, checkValidity() returns true while the validityState's validity property is false.
js
const output = document.getElementById("myOutput");
output.setCustomValidity("This object element is invalid.");
const validityState = output.validity;
console.log(validityState.valid); // false
console.log(validityState.customError); // true
console.log(output.checkValidity()); // true