Web Components & Shadow DOM

What is the purpose of ElementInternals in Web Components?

class CustomInput extends HTMLElement {
  constructor() {
    super();
    this._internals = this.attachInternals();
    this._internals.setFormValue('');
    this._internals.setValidity({
      valueMissing: true
    }, 'Please fill out this field.');
  }
}

To manage internal component state
To handle form association and validation
ElementInternals provides: 1) Form association capabilities for custom elements, 2) Methods for setting form values and validity states, 3) Access to form-related properties and ARIA information, 4) Integration with native form validation. This API is essential for creating custom form controls that work seamlessly with native form features.
To create private methods
To optimize performance

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