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ElementInternals: form property

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

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
form 77 79 98 No 64 16.4 77 77 98 55 16.4 12.0

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https://developer.mozilla.org/en-US/docs/Web/API/ElementInternals/form