<dialog> requestClose()

[jjagielka]

Describe the problem

Native <dialog> elements support now two methods to close it:

• close()
• requestClose() - triggers cancel event allowing to stop the closing

The latter is a new addition but seems to be available on all browsers:
https://developer.mozilla.org/en-US/docs/Web/API/HTMLDialogElement/requestClose

Svelte does not define that function yet:

/** [MDN Reference](https://developer.mozilla.org/docs/Web/API/HTMLDialogElement) */
interface HTMLDialogElement extends HTMLElement {
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/HTMLDialogElement/open) */
    open: boolean;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/HTMLDialogElement/returnValue) */
    returnValue: string;
    /**
     * Closes the dialog element.
     *
     * The argument, if provided, provides a return value.
     *
     * [MDN Reference](https://developer.mozilla.org/docs/Web/API/HTMLDialogElement/close)
     */
    close(returnValue?: string): void;
    /**
     * Displays the dialog element.
     *
     * [MDN Reference](https://developer.mozilla.org/docs/Web/API/HTMLDialogElement/show)
     */
    show(): void;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/HTMLDialogElement/showModal) */
    showModal(): void;
    addEventListener<K extends keyof HTMLElementEventMap>(type: K, listener: (this: HTMLDialogElement, ev: HTMLElementEventMap[K]) => any, options?: boolean | AddEventListenerOptions): void;
    addEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;
    removeEventListener<K extends keyof HTMLElementEventMap>(type: K, listener: (this: HTMLDialogElement, ev: HTMLElementEventMap[K]) => any, options?: boolean | EventListenerOptions): void;
    removeEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | EventListenerOptions): void;
}

Describe the proposed solution

Add the method requestClose to HTMLDialogElement:

/*
 * [MDN Reference](https://developer.mozilla.org/docs/Web/API/HTMLDialogElement/requestClose)
 */
requestClose(returnValue?: string): void;

Importance

nice to have