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pieced-portal/src/components/ui/modal.tsx
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keyboard radiogroup, modal focus trap, nav session hydration
2026-05-29 22:46:03 +02:00

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4.4 KiB
TypeScript

"use client";
import { useEffect, useRef } from "react";
import { createPortal } from "react-dom";
interface Props {
open: boolean;
/** Called when user clicks the backdrop or presses Escape. */
onClose: () => void;
children: React.ReactNode;
/**
* ARIA label fallback when no labelled element exists inside.
* Optional; if you have a heading inside the modal with id, set
* `aria-labelledby` on a wrapper instead.
*/
ariaLabel?: string;
}
const FOCUSABLE =
'a[href],button:not([disabled]),textarea:not([disabled]),input:not([disabled]),select:not([disabled]),[tabindex]:not([tabindex="-1"])';
/**
* Portal-based modal.
*
* Why a portal
* ------------
* `position: fixed` becomes positioned relative to a transformed
* ancestor's containing block, not the viewport, when ANY ancestor
* has a `transform`, `perspective`, or `filter` applied. Our
* `animate-in` utility sets `transform: translateY(0)` on a lot of
* dashboard/tenant-detail containers, which broke modals rendered as
* in-place children — they centred to the panel they lived in, not to
* the page. Rendering at `document.body` via `createPortal` escapes
* every containing-block ancestor and gives us true viewport coords.
*
* UX / a11y details
* -----------------
* - Backdrop click triggers `onClose` (only when the click target IS
* the backdrop, not the panel inside).
* - Escape triggers `onClose`.
* - `body` overflow is locked while open so background content doesn't
* scroll behind the modal.
* - Focus is moved into the panel on open, trapped within it while open
* (Tab / Shift+Tab cycle), and restored to the previously focused
* element on close — so keyboard and screen-reader users can't tab
* out to the inert page behind the dialog.
*/
export function Modal({ open, onClose, children, ariaLabel }: Props) {
const closeRef = useRef(onClose);
closeRef.current = onClose;
const panelRef = useRef<HTMLDivElement>(null);
useEffect(() => {
if (!open) return;
// Remember what had focus so we can restore it on close.
const previouslyFocused = document.activeElement as HTMLElement | null;
// Lock background scroll.
const previousOverflow = document.body.style.overflow;
document.body.style.overflow = "hidden";
// Move focus into the dialog — first focusable element, else the
// panel itself (it carries tabIndex={-1}).
const panel = panelRef.current;
const focusables = panel
? Array.from(panel.querySelectorAll<HTMLElement>(FOCUSABLE))
: [];
(focusables[0] ?? panel)?.focus();
const onKey = (e: KeyboardEvent) => {
if (e.key === "Escape") {
closeRef.current();
return;
}
if (e.key !== "Tab" || !panel) return;
// Re-query each time — modal content can change between tabs.
const items = Array.from(
panel.querySelectorAll<HTMLElement>(FOCUSABLE)
).filter((el) => el.offsetParent !== null || el === document.activeElement);
if (items.length === 0) {
e.preventDefault();
panel.focus();
return;
}
const first = items[0];
const last = items[items.length - 1];
const active = document.activeElement;
if (e.shiftKey) {
if (active === first || active === panel) {
e.preventDefault();
last.focus();
}
} else if (active === last) {
e.preventDefault();
first.focus();
}
};
window.addEventListener("keydown", onKey);
return () => {
document.body.style.overflow = previousOverflow;
window.removeEventListener("keydown", onKey);
// Restore focus to the trigger (if it's still in the document).
if (previouslyFocused && document.contains(previouslyFocused)) {
previouslyFocused.focus();
}
};
}, [open]);
if (!open) return null;
if (typeof document === "undefined") return null;
return createPortal(
<div
className="fixed inset-0 z-50 flex items-center justify-center p-4 bg-black/60 backdrop-blur-sm"
onClick={(e) => {
if (e.target === e.currentTarget) onClose();
}}
>
<div
ref={panelRef}
role="dialog"
aria-modal="true"
aria-label={ariaLabel}
tabIndex={-1}
className="bg-surface-1 border border-border rounded-xl p-6 max-w-md w-full max-h-[90vh] overflow-y-auto focus:outline-none"
>
{children}
</div>
</div>,
document.body
);
}