The HTMLOutputElement interface provides properties and methods (beyond those inherited from HTMLElement) for manipulating the layout and presentation of <output> elements.

This interface also inherits properties from its parent, HTMLElement.

HTMLOutputElement.defaultValue

A string representing the default value of the element, initially the empty string.

HTMLOutputElement.form Read only

An HTMLFormElement indicating the form associated with the control, reflecting the form HTML attribute if it is defined.

HTMLOutputElement.htmlFor Read only

A DOMTokenList reflecting the for HTML attribute, containing a list of IDs of other elements in the same document that contribute to (or otherwise affect) the calculated value.

HTMLOutputElement.labels Read only

A NodeList of <label> elements associated with the element.

HTMLOutputElement.name

A string reflecting the name HTML attribute, containing the name for the control that is submitted with form data.

HTMLOutputElement.type Read only

The string "output".

HTMLOutputElement.validationMessage Read only

A string representing a localized message that describes the validation constraints that the control does not satisfy (if any). This is the empty string if the control is not a candidate for constraint validation (willValidate is false), or it satisfies its constraints.

HTMLOutputElement.validity Read only

A ValidityState representing the validity states that this element is in.

HTMLOutputElement.value

A string representing the value of the contents of the elements. Behaves like the Node.textContent property.

HTMLOutputElement.willValidate Read only

A boolean value indicating whether the element is a candidate for constraint validation.

This interface also inherits methods from its parent, HTMLElement.

HTMLOutputElement.checkValidity()

Checks the validity of the element and returns a boolean value holding the check result.

HTMLOutputElement.reportValidity()

This method reports the problems with the constraints on the element, if any, to the user. If there are problems, fires an invalid event at the element, and returns false; if there are no problems, it returns true.

When the problem is reported, the user agent may focus the element and change the scrolling position of the document or perform some other action that brings the element to the user's attention. User agents may report more than one constraint violation if this element suffers from multiple problems at once. If the element is not rendered, then the user agent may report the error for the running script instead of notifying the user.

HTMLOutputElement.setCustomValidity()

Sets a custom validity message for the element. If this message is not the empty string, then the element is suffering from a custom validity error, and does not validate.

This element behaves in one of two modes: default mode and value mode.

Initially, the element is in default mode, and so the contents of the element represent both the value of the element and its default value.

If the element is in default mode when the descendants of the element are changed in any way, the defaultValue property is set to the value of the textContent property.

Resetting the form puts the element into default mode, and sets the textContent property to the value of the defaultValue property.

The element goes into value mode when the contents of the value property are set. The value property otherwise behaves like the textContent property. When the element is in value mode, the default value is accessible only through the defaultValue property.

• The HTML element implementing this interface: <output>.