function reset_focus()

in kit/svelteKitCustomClient/client.js [1983:2047]

• 40 lines of code
• 13 McCabe index (conditional complexity)

function reset_focus() {
	const autofocus = document.querySelector("[autofocus]");
	if (autofocus) {
		// @ts-ignore
		autofocus.focus();
	} else {
		// Reset page selection and focus
		// We try to mimic browsers' behaviour as closely as possible by targeting the
		// first scrollable region, but unfortunately it's not a perfect match — e.g.
		// shift-tabbing won't immediately cycle up from the end of the page on Chromium
		// See https://html.spec.whatwg.org/multipage/interaction.html#get-the-focusable-area
		const root = document.body;
		const tabindex = root.getAttribute("tabindex");

		root.tabIndex = -1;
		// @ts-expect-error
		root.focus({ preventScroll: true, focusVisible: false });

		// restore `tabindex` as to prevent `root` from stealing input from elements
		if (tabindex !== null) {
			root.setAttribute("tabindex", tabindex);
		} else {
			root.removeAttribute("tabindex");
		}

		// capture current selection, so we can compare the state after
		// snapshot restoration and afterNavigate callbacks have run
		const selection = getSelection();

		if (selection && selection.type !== "None") {
			/** @type {Range[]} */
			const ranges = [];

			for (let i = 0; i < selection.rangeCount; i += 1) {
				ranges.push(selection.getRangeAt(i));
			}

			setTimeout(() => {
				if (selection.rangeCount !== ranges.length) return;

				for (let i = 0; i < selection.rangeCount; i += 1) {
					const a = ranges[i];
					const b = selection.getRangeAt(i);

					// we need to do a deep comparison rather than just `a !== b` because
					// Safari behaves differently to other browsers
					if (
						a.commonAncestorContainer !== b.commonAncestorContainer ||
						a.startContainer !== b.startContainer ||
						a.endContainer !== b.endContainer ||
						a.startOffset !== b.startOffset ||
						a.endOffset !== b.endOffset
					) {
						return;
					}
				}

				// if the selection hasn't changed (as a result of an element being (auto)focused,
				// or a programmatic selection, we reset everything as part of the navigation)
				// fixes https://github.com/sveltejs/kit/issues/8439
				selection.removeAllRanges();
			});
		}
	}
}