HTMLOutputElement: setCustomValidity() method

The setCustomValidity() method of the HTMLOutputElement interface sets the custom validity message for the <output> element. Use the empty string to indicate that the element does not have a custom validity error.

The <output> element is not a candidate for constraint validation. The reportValidity() method will not cause the custom error message to be displayed to the user, but does set the customError property of the element's ValidityState object to true and the valid property to false.

Syntax

setCustomValidity(string)

Parameters

string

The string containing the error message. The empty string removes any custom validity errors.

Return value

None (undefined).

Examples

In this example, if the <output>'s value is not a non-zero number, we set a custom error message. If it is a number, we set the custom error to an empty string:

const cart = document.getElementById("cart-form");
const total = cart.elements("total");
if (parseFloat(total.value)) {
  errorOutput.setCustomValidity("");
} else {
  errorOutput.setCustomValidity("There is an error");
}

Specifications

Browser compatibility

See also

• <output>
• HTMLOutputElement
• HTMLOutputElement.validity
• HTMLOutputElement.checkValidity()
• HTMLOutputElement.reportValidity()
• Form validation.
• Learn: Client-side form validation
• Guide: Constraint validation
• CSS :valid and :invalid pseudo-classes