ElementInternals: form property

Baseline 2023
Newly available

Since March 2023, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

The form read-only property of the ElementInternals interface returns the HTMLFormElement associated with this element.

Value

Examples

The following example shows a custom checkbox component inside a form with an ID of myForm. Printing form.length to the console, gives us the value of HTMLFormElement.length.

html
<form id="myForm">
  <custom-checkbox id="custom-checkbox"></custom-checkbox>
  <custom-label for="custom-checkbox">Join newsletter</custom-label>
</form>
js
class CustomCheckbox extends HTMLElement {
  static formAssociated = true;
  #internals;

  constructor() {
    super();
    this.#internals = this.attachInternals();
  }

  connectedCallback() {
    console.log(this.#internals.form.length);
  }
}

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

Specifications

Specification
HTML
# dom-elementinternals-form

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
form

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support