The ElementInternals interface of the Document Object Model gives web developers a way to allow custom elements to fully participate in HTML forms. It provides utilities for working with these elements in the same way you would work with any standard HTML form element, and also exposes the Accessibility Object Model to the element.

This interface has no constructor. An ElementInternals object is returned when calling HTMLElement.attachInternals().

ElementInternals.shadowRoot Read only

Returns the ShadowRoot object associated with this element.

ElementInternals.form Read only

Returns the HTMLFormElement associated with this element.

ElementInternals.states Read only Experimental

Returns the CustomStateSet associated with this element.

ElementInternals.willValidate Read only

A boolean value which returns true if the element is a submittable element that is a candidate for constraint validation.

ElementInternals.validity Read only

Returns a ValidityState object which represents the different validity states the element can be in, with respect to constraint validation.

ElementInternals.validationMessage Read only

A string containing the validation message of this element.

ElementInternals.labels Read only

Returns a NodeList of all of the label elements associated with this element.

The ElementInternals interface includes the following properties, defined on the ARIAMixin mixin.

ElementInternals.ariaAtomic

A string reflecting the aria-atomic attribute, which indicates whether assistive technologies will present all, or only parts of, the changed region based on the change notifications defined by the aria-relevant attribute.

ElementInternals.ariaAutoComplete

A string reflecting the aria-autocomplete attribute, which indicates whether inputting text could trigger display of one or more predictions of the user's intended value for a combobox, searchbox, or textbox and specifies how predictions would be presented if they were made.

ElementInternals.ariaBusy

A string reflecting the aria-busy attribute, which indicates whether an element is being modified, as assistive technologies may want to wait until the modifications are complete before exposing them to the user.

ElementInternals.ariaChecked

A string reflecting the aria-checked attribute, which indicates the current "checked" state of checkboxes, radio buttons, and other widgets that have a checked state.

ElementInternals.ariaColCount

A string reflecting the aria-colcount attribute, which defines the number of columns in a table, grid, or treegrid.

ElementInternals.ariaColIndex

A string reflecting the aria-colindex attribute, which defines an element's column index or position with respect to the total number of columns within a table, grid, or treegrid.

ElementInternals.ariaColSpan

A string reflecting the aria-colspan attribute, which defines the number of columns spanned by a cell or gridcell within a table, grid, or treegrid.

ElementInternals.ariaCurrent

A string reflecting the aria-current attribute, which indicates the element that represents the current item within a container or set of related elements.

ElementInternals.ariaDescription

A string reflecting the aria-description attribute, which defines a string value that describes or annotates the current ElementInternals.

ElementInternals.ariaDisabled

A string reflecting the aria-disabled attribute, which indicates that the element is perceivable but disabled, so it is not editable or otherwise operable.

ElementInternals.ariaExpanded

A string reflecting the aria-expanded attribute, which indicates whether a grouping element owned or controlled by this element is expanded or collapsed.

ElementInternals.ariaHasPopup

A string reflecting the aria-haspopup attribute, which indicates the availability and type of interactive popup element, such as menu or dialog, that can be triggered by an ElementInternals.

ElementInternals.ariaHidden

A string reflecting the aria-hidden attribute, which indicates whether the element is exposed to an accessibility API.

ElementInternals.ariaKeyShortcuts

A string reflecting the aria-keyshortcuts attribute, which indicates keyboard shortcuts that an author has implemented to activate or give focus to an ElementInternals.

ElementInternals.ariaLabel

A string reflecting the aria-label attribute, which defines a string value that labels the current ElementInternals.

ElementInternals.ariaLevel

A string reflecting the aria-level attribute, which defines the hierarchical level of an element within a structure.

ElementInternals.ariaLive

A string reflecting the aria-live attribute, which indicates that an element will be updated, and describes the types of updates the user agents, assistive technologies, and user can expect from the live region.

ElementInternals.ariaModal

A string reflecting the aria-modal attribute, which indicates whether an element is modal when displayed.

ElementInternals.ariaMultiline

A string reflecting the aria-multiline attribute, which indicates whether a text box accepts multiple lines of input or only a single line.

ElementInternals.ariaMultiSelectable

A string reflecting the aria-multiselectable attribute, which indicates that the user may select more than one item from the current selectable descendants.

ElementInternals.ariaOrientation

A string reflecting the aria-orientation attribute, which indicates whether the element's orientation is horizontal, vertical, or unknown/ambiguous.

ElementInternals.ariaPlaceholder

A string reflecting the aria-placeholder attribute, which defines a short hint intended to aid the user with data entry when the control has no value.

ElementInternals.ariaPosInSet

A string reflecting the aria-posinset attribute, which defines an element's number or position in the current set of listitems or treeitems.

ElementInternals.ariaPressed

A string reflecting the aria-pressed attribute, which indicates the current "pressed" state of toggle buttons.

ElementInternals.ariaReadOnly

A string reflecting the aria-readonly attribute, which indicates that the element is not editable, but is otherwise operable.

ElementInternals.ariaRelevant Non-standard

A string reflecting the aria-relevant attribute, which indicates what notifications the user agent will trigger when the accessibility tree within a live region is modified. This is used to describe what changes in an aria-live region are relevant and should be announced.

ElementInternals.ariaRequired

A string reflecting the aria-required attribute, which indicates that user input is required on the element before a form may be submitted.

ElementInternals.role

A string which contains an ARIA role. A full list of ARIA roles can be found on the ARIA techniques page.

ElementInternals.ariaRoleDescription

A string reflecting the aria-roledescription attribute, which defines a human-readable, author-localized description for the role of an Element.

ElementInternals.ariaRowCount

A string reflecting the aria-rowcount attribute, which defines the total number of rows in a table, grid, or treegrid.

ElementInternals.ariaRowIndex

A string reflecting the aria-rowindex attribute, which defines an element's row index or position with respect to the total number of rows within a table, grid, or treegrid.

ElementInternals.ariaRowSpan

A string reflecting the aria-rowspan attribute, which defines the number of rows spanned by a cell or gridcell within a table, grid, or treegrid.

ElementInternals.ariaSelected

A string reflecting the aria-selected attribute, which indicates the current "selected" state of elements that have a selected state.

ElementInternals.ariaSetSize

A string reflecting the aria-setsize attribute, which defines the number of items in the current set of listitems or treeitems.

ElementInternals.ariaSort

A string reflecting the aria-sort attribute, which indicates if items in a table or grid are sorted in ascending or descending order.

ElementInternals.ariaValueMax

A string reflecting the aria-valueMax attribute, which defines the maximum allowed value for a range widget.

ElementInternals.ariaValueMin

A string reflecting the aria-valueMin attribute, which defines the minimum allowed value for a range widget.

ElementInternals.ariaValueNow

A string reflecting the aria-valueNow attribute, which defines the current value for a range widget.

ElementInternals.ariaValueText

A string reflecting the aria-valuetext attribute, which defines the human-readable text alternative of aria-valuenow for a range widget.

ElementInternals.setFormValue()

Sets the element's submission value and state, communicating these to the user agent.

ElementInternals.setValidity()

Sets the validity of the element.

ElementInternals.checkValidity()

Checks if an element meets any constraint validation rules applied to it.

ElementInternals.reportValidity()

Checks if an element meets any constraint validation rules applied to it, and also sends a validation message to the user agent.

The following example demonstrates how to create a custom form-associated element with HTMLElement.attachInternals.

class CustomCheckbox extends HTMLElement {
  static formAssociated = true;

  constructor() {
    super();
    this.internals_ = this.attachInternals();
  }

  // …
}

window.customElements.define("custom-checkbox", CustomCheckbox);

let element = document.createElement("custom-checkbox");
let form = document.createElement("form");

// Append element to form to associate it
form.appendChild(element);

console.log(element.internals_.form);
// expected output: <form><custom-checkbox></custom-checkbox></form>

• More capable form controls
• Creating custom form controls with ElementInternals
• ElementInternals polyfill