Manage nested dialogs through a central stack

This commit is contained in:
2026-07-21 03:18:08 +02:00
parent 183bf7aef0
commit 1839693575
7 changed files with 653 additions and 8 deletions

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function assert(condition: unknown, message = "assertion failed"): void {
if (!condition) throw new Error(message);
}
function assertEqual<T>(actual: T, expected: T, message = "values should be equal"): void {
if (actual !== expected) throw new Error(`${message}: expected ${String(expected)}, got ${String(actual)}`);
}
import { renderToStaticMarkup } from "react-dom/server";
import Dialog from "../src/components/Dialog";
import {
focusDialogOnOpen,
handleDialogKeyDown,
restoreDialogFocus,
shouldCloseDialogOnBackdrop,
trapDialogFocus
} from "../src/components/dialogInteractions";
import {
handleTopDialogKeyDown,
nextDialogActivationOrder,
registerDialog,
resetDialogStackForTests
} from "../src/components/dialogStack";
type FocusableFixture = HTMLElement & { focusCount: number; attributes: Map<string, string> };
function focusableFixture({ connected = true, hidden = false }: { connected?: boolean; hidden?: boolean } = {}): FocusableFixture {
const attributes = new Map<string, string>();
if (hidden) attributes.set("hidden", "");
const fixture = {
attributes,
focusCount: 0,
tabIndex: 0,
isConnected: connected,
getAttribute: (name: string) => attributes.get(name) ?? null,
hasAttribute: (name: string) => attributes.has(name),
setAttribute: (name: string, value: string) => attributes.set(name, value),
removeAttribute: (name: string) => attributes.delete(name),
closest: () => attributes.has("hidden") || attributes.has("inert") || attributes.get("aria-hidden") === "true" ? fixture : null,
focus() {
fixture.focusCount += 1;
}
};
return fixture as unknown as FocusableFixture;
}
function panelFixture(elements: FocusableFixture[], autofocus?: FocusableFixture) {
const panel = focusableFixture();
panel.tabIndex = -1;
Object.assign(panel, {
contains: (element: Element | null) => element === panel || elements.includes(element as FocusableFixture),
querySelectorAll: () => elements,
querySelector: (selector: string) => selector === "[autofocus]" ? (autofocus ?? null) : null
});
return panel;
}
function keyboardEvent(key: string, shiftKey = false) {
const fixture = {
key,
shiftKey,
prevented: 0,
preventDefault() {
fixture.prevented += 1;
}
};
return fixture;
}
const markup = renderToStaticMarkup(
<Dialog open title="Dialog title" onClose={() => undefined}>
<button type="button">First action</button>
</Dialog>
);
assert(markup.includes('role="dialog"'), "dialog semantics are preserved");
assert(markup.includes('aria-modal="true"'), "modal semantics are preserved");
assert(markup.includes('data-dialog-stack-state="topmost"'), "dialog exposes its initial stack state");
assert(markup.includes('tabindex="-1"'), "dialog panel can receive fallback focus");
const first = focusableFixture();
const requested = focusableFixture();
const entryPanel = panelFixture([first, requested], requested);
assertEqual(focusDialogOnOpen(entryPanel, null), requested, "autofocus target receives initial focus");
assertEqual(requested.focusCount, 1, "autofocus target is focused once");
const defaultEntryPanel = panelFixture([first]);
assertEqual(focusDialogOnOpen(defaultEntryPanel, null), first, "first available control receives initial focus");
assertEqual(first.focusCount, 1, "first available control is focused once");
const retained = focusableFixture();
const retainedPanel = panelFixture([retained]);
assertEqual(focusDialogOnOpen(retainedPanel, retained), retained, "existing focus inside the dialog is retained");
assertEqual(retained.focusCount, 0, "retained focus is not moved redundantly");
const emptyPanel = panelFixture([]);
assertEqual(focusDialogOnOpen(emptyPanel, null), emptyPanel, "panel receives focus when no control is available");
assertEqual(emptyPanel.focusCount, 1, "fallback panel is focused");
const boundaryFirst = focusableFixture();
const boundaryMiddle = focusableFixture();
const boundaryLast = focusableFixture();
const boundaryPanel = panelFixture([boundaryFirst, boundaryMiddle, boundaryLast]);
const forwardWrap = keyboardEvent("Tab");
assert(trapDialogFocus(boundaryPanel, forwardWrap, boundaryLast), "forward Tab wraps at the last control");
assertEqual(forwardWrap.prevented, 1, "forward wrap prevents focus from leaving the dialog");
assertEqual(boundaryFirst.focusCount, 1, "forward wrap focuses the first control");
const backwardWrap = keyboardEvent("Tab", true);
assert(trapDialogFocus(boundaryPanel, backwardWrap, boundaryFirst), "Shift+Tab wraps at the first control");
assertEqual(backwardWrap.prevented, 1, "backward wrap prevents focus from leaving the dialog");
assertEqual(boundaryLast.focusCount, 1, "backward wrap focuses the last control");
const interiorTab = keyboardEvent("Tab");
assert(!trapDialogFocus(boundaryPanel, interiorTab, boundaryMiddle), "interior Tab keeps native focus order");
assertEqual(interiorTab.prevented, 0, "interior Tab is not prevented");
const outsideTab = keyboardEvent("Tab");
assert(trapDialogFocus(boundaryPanel, outsideTab, focusableFixture()), "focus cannot enter the modal from outside its boundary");
assertEqual(boundaryFirst.focusCount, 2, "outside focus is redirected to the first control");
let closeCount = 0;
const escape = keyboardEvent("Escape");
assert(handleDialogKeyDown(boundaryPanel, escape, boundaryFirst, true, () => { closeCount += 1; }), "Escape closes a closable dialog");
assertEqual(closeCount, 1, "Escape invokes onClose once");
assertEqual(escape.prevented, 0, "Escape preserves the existing default-event behavior");
const blockedEscape = keyboardEvent("Escape");
assert(!handleDialogKeyDown(boundaryPanel, blockedEscape, boundaryFirst, false, () => { closeCount += 1; }), "Escape is ignored while closing is disabled");
assertEqual(closeCount, 1, "disabled Escape does not invoke onClose");
const opener = focusableFixture();
assert(restoreDialogFocus(opener), "connected opener focus is restored");
assertEqual(opener.focusCount, 1, "opener receives restored focus once");
assert(!restoreDialogFocus(focusableFixture({ connected: false })), "removed opener is not focused");
const backdrop = {} as EventTarget;
const child = {} as EventTarget;
assert(shouldCloseDialogOnBackdrop(backdrop, backdrop, true, true), "direct backdrop press closes a closable dialog");
assert(!shouldCloseDialogOnBackdrop(child, backdrop, true, true), "presses inside the panel do not close the dialog");
assert(!shouldCloseDialogOnBackdrop(backdrop, backdrop, false, true), "backdrop closing can be disabled");
assert(!shouldCloseDialogOnBackdrop(backdrop, backdrop, true, false), "backdrop press respects closeDisabled");
resetDialogStackForTests();
const outerOpener = focusableFixture();
const parentOpener = focusableFixture();
const parentLast = focusableFixture();
const parentPanel = panelFixture([parentOpener, parentLast]);
const childFirst = focusableFixture();
const childLast = focusableFixture();
const childPanel = panelFixture([childFirst, childLast]);
const parentId = Symbol("parent-dialog");
const childId = Symbol("child-dialog");
const parentOrder = nextDialogActivationOrder();
const childOrder = nextDialogActivationOrder();
let parentCloseCount = 0;
let childCloseCount = 0;
let childCanClose = false;
// React may commit a nested child's effect before its parent effect. Activation
// order is allocated during render so the child must remain topmost either way.
const unregisterChild = registerDialog({
id: childId,
activationOrder: childOrder,
panel: childPanel,
restoreFocus: parentOpener,
canClose: () => childCanClose,
onClose: () => { childCloseCount += 1; }
}, parentOpener);
const unregisterParent = registerDialog({
id: parentId,
activationOrder: parentOrder,
panel: parentPanel,
restoreFocus: outerOpener,
canClose: () => true,
onClose: () => { parentCloseCount += 1; }
}, childFirst);
assertEqual(parentPanel.getAttribute("data-dialog-stack-state"), "underlying", "parent dialog is marked as underlying");
assert(parentPanel.hasAttribute("inert"), "parent dialog is inert while a child is open");
assertEqual(parentPanel.getAttribute("aria-hidden"), "true", "parent dialog is hidden from assistive technology");
assertEqual(parentPanel.getAttribute("aria-modal"), null, "underlying dialog no longer claims modal semantics");
assertEqual(childPanel.getAttribute("data-dialog-stack-state"), "topmost", "child dialog is marked as topmost");
assertEqual(childPanel.getAttribute("aria-modal"), "true", "child dialog owns modal semantics");
const stackedTab = keyboardEvent("Tab");
const parentFocusBeforeTab = parentOpener.focusCount;
assert(handleTopDialogKeyDown(stackedTab, childLast), "topmost dialog traps Tab");
assertEqual(stackedTab.prevented, 1, "stacked Tab wrapping is prevented once");
assertEqual(parentOpener.focusCount, parentFocusBeforeTab, "underlying dialog does not process Tab");
const disabledStackedEscape = keyboardEvent("Escape");
assert(!handleTopDialogKeyDown(disabledStackedEscape, childFirst), "disabled child ignores Escape without falling through");
assertEqual(childCloseCount, 0, "disabled child remains open");
assertEqual(parentCloseCount, 0, "disabled child Escape does not close the parent");
childCanClose = true;
const stackedEscape = keyboardEvent("Escape");
assert(handleTopDialogKeyDown(stackedEscape, childFirst), "topmost dialog handles Escape");
assertEqual(childCloseCount, 1, "one Escape closes the child once");
assertEqual(parentCloseCount, 0, "one Escape does not close the parent");
const parentFocusBeforeChildClose = parentOpener.focusCount;
unregisterChild();
assertEqual(parentOpener.focusCount, parentFocusBeforeChildClose + 1, "closing the child restores focus inside the parent");
assert(!parentPanel.hasAttribute("inert"), "parent dialog becomes interactive after the child closes");
assertEqual(parentPanel.getAttribute("aria-hidden"), null, "parent dialog returns to the accessibility tree");
assertEqual(parentPanel.getAttribute("aria-modal"), "true", "parent dialog regains modal semantics");
assertEqual(parentPanel.getAttribute("data-dialog-stack-state"), "topmost", "parent dialog becomes topmost");
const parentEscape = keyboardEvent("Escape");
assert(handleTopDialogKeyDown(parentEscape, parentOpener), "parent handles Escape after child cleanup");
assertEqual(parentCloseCount, 1, "parent closes only on its own Escape handling");
unregisterParent();
assertEqual(outerOpener.focusCount, 1, "closing the final dialog restores the outer opener");
assert(!handleTopDialogKeyDown(keyboardEvent("Escape"), outerOpener), "keyboard handling stops when the stack is empty");
resetDialogStackForTests();
const forcedOuterOpener = focusableFixture();
const removedParentOpener = focusableFixture();
const removedParentPanel = panelFixture([removedParentOpener]);
const forcedChildControl = focusableFixture();
const forcedChildPanel = panelFixture([forcedChildControl]);
const unregisterForcedParent = registerDialog({
id: Symbol("forced-parent-dialog"),
activationOrder: nextDialogActivationOrder(),
panel: removedParentPanel,
restoreFocus: forcedOuterOpener,
canClose: () => true
}, forcedOuterOpener);
const unregisterForcedChild = registerDialog({
id: Symbol("forced-child-dialog"),
activationOrder: nextDialogActivationOrder(),
panel: forcedChildPanel,
restoreFocus: removedParentOpener,
canClose: () => true
}, removedParentOpener);
unregisterForcedParent();
Object.assign(removedParentOpener, { isConnected: false });
unregisterForcedChild();
assertEqual(forcedOuterOpener.focusCount, 1, "removing a dialog tree restores the nearest connected outer opener");
resetDialogStackForTests();
const strictModeOpener = focusableFixture();
const strictModeControl = focusableFixture();
const strictModePanel = panelFixture([strictModeControl]);
const strictModeRegistration = {
id: Symbol("strict-mode-dialog"),
activationOrder: nextDialogActivationOrder(),
panel: strictModePanel,
restoreFocus: strictModeOpener,
canClose: () => true
};
const unregisterStrictModeFirstPass = registerDialog(strictModeRegistration, strictModeOpener);
unregisterStrictModeFirstPass();
const unregisterStrictModeReplay = registerDialog(strictModeRegistration, strictModeOpener);
assertEqual(strictModeControl.focusCount, 2, "StrictMode effect replay returns focus to the dialog");
assertEqual(strictModeOpener.focusCount, 1, "StrictMode cleanup restores the opener before replay");
unregisterStrictModeReplay();
assertEqual(strictModeOpener.focusCount, 2, "StrictMode replay cleanup restores focus without leaving a stack entry");
assert(!handleTopDialogKeyDown(keyboardEvent("Escape"), strictModeOpener), "StrictMode replay leaves no stale topmost dialog");
resetDialogStackForTests();
let keydownListenerAdds = 0;
let keydownListenerRemovals = 0;
Object.defineProperty(globalThis, "window", {
configurable: true,
value: {
addEventListener(type: string) {
if (type === "keydown") keydownListenerAdds += 1;
},
removeEventListener(type: string) {
if (type === "keydown") keydownListenerRemovals += 1;
},
getComputedStyle() {
return { display: "block", visibility: "visible" };
}
}
});
try {
const listenerOuter = focusableFixture();
const listenerParentPanel = panelFixture([focusableFixture()]);
const listenerChildPanel = panelFixture([focusableFixture()]);
const unregisterListenerParent = registerDialog({
id: Symbol("listener-parent"),
activationOrder: nextDialogActivationOrder(),
panel: listenerParentPanel,
restoreFocus: listenerOuter,
canClose: () => true
}, listenerOuter);
const unregisterListenerChild = registerDialog({
id: Symbol("listener-child"),
activationOrder: nextDialogActivationOrder(),
panel: listenerChildPanel,
restoreFocus: listenerParentPanel,
canClose: () => true
}, listenerParentPanel);
assertEqual(keydownListenerAdds, 1, "one window keyboard listener serves the whole dialog stack");
unregisterListenerChild();
assertEqual(keydownListenerRemovals, 0, "keyboard listener remains while a parent dialog is open");
unregisterListenerParent();
assertEqual(keydownListenerRemovals, 1, "keyboard listener is removed after the final dialog closes");
} finally {
resetDialogStackForTests();
Reflect.deleteProperty(globalThis, "window");
}