HTMLElement: attachInternals() method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2023.
The HTMLElement.attachInternals() method returns an ElementInternals object.
This method allows a custom element to participate in HTML forms. The ElementInternals interface 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.
Syntax
attachInternals()
Parameters
None.
Return value
An ElementInternals object.
Exceptions
NotSupportedErrorDOMException-
Thrown if the element is not a custom element.
NotSupportedErrorDOMException-
Thrown if the "internals" feature was disabled as part of the element definition.
NotSupportedErrorDOMException-
Thrown if this method is called twice on the same element.
Examples
The following example demonstrates how to create a custom form-associated element with HTMLElement.attachInternals. The ElementInternals.form property is then printed to the console to demonstrate that we have an ElementInternals object.
class CustomCheckbox extends HTMLElement {
static formAssociated = true;
constructor() {
super();
this.internals_ = this.attachInternals();
}
// …
}
window.customElements.define("custom-checkbox", CustomCheckbox);
let element = document.getElementById("custom-checkbox");
console.log(element.internals_.form);
Specifications
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| HTML # dom-attachinternals |
Browser compatibility
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attachInternals
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Legend
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- Full support
- Full support
- See implementation notes.