Function findFocusableElement

packages/base/src/util/FocusableElements.ts:50–123

(container: HTMLElement, forward: boolean, startFromContainer?: boolean)

};

const findFocusableElement = async (container: HTMLElement, forward: boolean, startFromContainer?: boolean): FocusableElementPromise => {
	let child: HTMLElement | undefined;
	let assignedElements;
	let currentIndex = -1;

	if (container.shadowRoot) {
		child = forward ? container.shadowRoot.firstElementChild as HTMLElement : container.shadowRoot.lastElementChild as HTMLElement;
	} else if (container instanceof HTMLSlotElement && container.assignedNodes()) {
		assignedElements = container.assignedElements();
		currentIndex = forward ? 0 : assignedElements.length - 1;
		child = assignedElements[currentIndex] as HTMLElement;
	} else if (startFromContainer) {
		child = container;
	} else {
		child = forward ? container.firstElementChild as HTMLElement : container.lastElementChild as HTMLElement;
	}

	let focusableDescendant;

	/* eslint-disable no-await-in-loop */

	while (child) {
		const originalChild: HTMLElement | undefined = child;

		if (!isElementHidden(originalChild) && !isUI5ElementWithNegativeTabIndex(originalChild)) {
			if (instanceOfUI5Element(child)) {
				// getDomRef is used because some components mark their focusable ref in an inner
				// html but there might also be focusable targets outside of it
				// as an example - TreeItemBase
				// div - root of the component returned by getDomRef()
				// 	li.ui5-li-tree - returned by getFocusDomRef() and may not be focusable (ItemNavigation manages tabindex)
				// 	ul.subtree - may still contain focusable targets (sub nodes of the tree item)
				await child._waitForDomRef();
				child = child.getDomRef();
			}

			if (!child || isElementHidden(child)) {
				return null;
			}

			if (child.nodeType === 1 && isElemFocusable(child) && !isFocusTrap(child)) {
				if (isElementClickable(child)) {
					return (child && typeof child.focus === "function") ? child : null;
				}

				focusableDescendant = await findFocusableElement(child, forward);

				// check if it is a keyboard focusable scroll container
				if (!isSafari() && !focusableDescendant && isScrollable(child)) {
					return (child && typeof child.focus === "function") ? child : null;
				}

				if (focusableDescendant) {
					return (focusableDescendant && typeof focusableDescendant.focus === "function") ? focusableDescendant : null;
				}
			}
		}