Jesse_Chen
27 lines
855 B
TypeScript
27 lines
855 B
TypeScript
const focusableSelector = [
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"a[href]",
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"button:not([disabled])",
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"input:not([disabled])",
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"select:not([disabled])",
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"textarea:not([disabled])",
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"[tabindex]:not([tabindex='-1'])",
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].join(",");
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export function keepFocusWithin(event: KeyboardEvent, container: HTMLElement) {
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if (event.key !== "Tab") return;
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const focusable = Array.from(container.querySelectorAll<HTMLElement>(focusableSelector))
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.filter((element) => element.getAttribute("aria-hidden") !== "true" && element.offsetParent !== null);
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const first = focusable[0];
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const last = focusable[focusable.length - 1];
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if (!first || !last) return;
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if (event.shiftKey && document.activeElement === first) {
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event.preventDefault();
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last.focus();
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} else if (!event.shiftKey && document.activeElement === last) {
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event.preventDefault();
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first.focus();
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}
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}
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