The <keygen> elements expose the HTMLKeygenElement interface, which provides special properties and methods (beyond the regular element object interface they also have available to them by inheritance) for manipulating the layout and presentation of keygen elements.
The read-only HTMLLabelElement.control property returns a reference to the control (in the form of an object of type HTMLElement or one of its derivatives) with which the <label> element is associated, or null if the label isn't associated with a control.
The read-only HTMLLabelElement.form property returns an HTMLFormElement object which represents the form of which the label's associated control is a part, or null if there is either no associated control, or if that control isn't in a form.
The HTMLLinkElement.relList read-only property reflects the rel attribute. It is a live DOMTokenList containing the set of link types indicating the relationship between the resource represented by the <link> element and the current document.
The HTMLMediaElement interface adds to HTMLElement the properties and methods needed to support basic media-related capabilities that are common to audio and video. The HTMLVideoElement and HTMLAudioElement elements both inherit this interface.
The HTMLMediaElement.buffered read-only property returns a new TimeRanges object that indicates the ranges of the media source that the browser has buffered (if any) at the moment the buffered property is accessed.
The HTMLMediaElement.currentSrc property contains the absolute URL of the chosen media resource. This could happen, for example, if the web server selects a media file based on the resolution of the user's display. The value is an empty string if the networkState property is EMPTY.
The HTML <meter> elements expose the HTMLMeterElement interface, which provides special properties and methods (beyond the HTMLElement object interface they also have available to them by inheritance) for manipulating the layout and presentation of <meter> elements.
The HTMLOptGroupElement interface provides special properties and methods (beyond the regular HTMLElement object interface they also have available to them by inheritance) for manipulating the layout and presentation of <optgroup> elements.
HTMLOptionsCollection is an interface representing a collection of HTML option elements (in document order) and offers methods and properties for traversing the list as well as optionally altering its items. This type is returned solely by the "options" property of select.
The HTMLSelectElement.checkValidity() method checks whether the element has any constraints and whether it satisfies them. If the element fails its constraints, the browser fires a cancelable invalid event at the element, and then returns false.
The HTMLSelectElement.setCustomValidity() method sets the custom validity message for the selection element to the specified message. Use the empty string to indicate that the element does not have a custom validity error.