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Fix React 18 strict mode breaking spotlight search

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This code originally held an array of refs. But these refs were unset
just before sorting leading to errors.

For the fix, I've used a callback ref to add/remove the DOM elements
to/from the array in state. This way there's nothing that could possibly
mutate just before sort.
This commit is contained in:
R Midhun Suresh 2024-11-13 00:28:32 +05:30
parent 2f8e98242c
commit 0faf298e05
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3 changed files with 151 additions and 133 deletions
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166
src/accessibility/RovingTabIndex.tsx
View file

@ -10,7 +10,6 @@ import React, {
createContext,
useCallback,
useContext,
useEffect,
useMemo,
useRef,
useReducer,
@ -22,7 +21,7 @@ import React, {
import { getKeyBindingsManager } from "../KeyBindingsManager";
import { KeyBindingAction } from "./KeyboardShortcuts";
import { FocusHandler, Ref } from "./roving/types";
import { FocusHandler } from "./roving/types";
/**
* Module to simplify implementing the Roving TabIndex accessibility technique
@ -49,8 +48,8 @@ export function checkInputableElement(el: HTMLElement): boolean {
}
export interface IState {
activeRef?: Ref;
refs: Ref[];
activeNode?: HTMLElement;
nodes: HTMLElement[];
}
export interface IContext {
@ -60,7 +59,7 @@ export interface IContext {
export const RovingTabIndexContext = createContext<IContext>({
state: {
refs: [], // list of refs in DOM order
nodes: [], // list of nodes in DOM order
},
dispatch: () => {},
});
@ -76,7 +75,7 @@ export enum Type {
export interface IAction {
type: Exclude<Type, Type.Update>;
payload: {
ref: Ref;
node: HTMLElement;
};
}
@ -87,12 +86,12 @@ interface UpdateAction {
type Action = IAction | UpdateAction;
const refSorter = (a: Ref, b: Ref): number => {
const nodeSorter = (a: HTMLElement, b: HTMLElement): number => {
if (a === b) {
return 0;
}
const position = a.current!.compareDocumentPosition(b.current!);
const position = a.compareDocumentPosition(b);
if (position & Node.DOCUMENT_POSITION_FOLLOWING || position & Node.DOCUMENT_POSITION_CONTAINED_BY) {
return -1;
@ -106,54 +105,56 @@ const refSorter = (a: Ref, b: Ref): number => {
export const reducer: Reducer<IState, Action> = (state: IState, action: Action) => {
switch (action.type) {
case Type.Register: {
if (!state.activeRef) {
// Our list of refs was empty, set activeRef to this first item
state.activeRef = action.payload.ref;
if (!state.activeNode) {
// Our list of nodes was empty, set activeNode to this first item
state.activeNode = action.payload.node;
}
if (state.nodes.includes(action.payload.node)) return state;
// Sadly due to the potential of DOM elements swapping order we can't do anything fancy like a binary insert
state.refs.push(action.payload.ref);
state.refs.sort(refSorter);
state.nodes.push(action.payload.node);
state.nodes.sort(nodeSorter);
return { ...state };
}
case Type.Unregister: {
const oldIndex = state.refs.findIndex((r) => r === action.payload.ref);
const oldIndex = state.nodes.findIndex((r) => r === action.payload.node);
if (oldIndex === -1) {
return state; // already removed, this should not happen
}
if (state.refs.splice(oldIndex, 1)[0] === state.activeRef) {
// we just removed the active ref, need to replace it
// pick the ref closest to the index the old ref was in
if (oldIndex >= state.refs.length) {
state.activeRef = findSiblingElement(state.refs, state.refs.length - 1, true);
if (state.nodes.splice(oldIndex, 1)[0] === state.activeNode) {
// we just removed the active node, need to replace it
// pick the node closest to the index the old node was in
if (oldIndex >= state.nodes.length) {
state.activeNode = findSiblingElement(state.nodes, state.nodes.length - 1, true);
} else {
state.activeRef =
findSiblingElement(state.refs, oldIndex) || findSiblingElement(state.refs, oldIndex, true);
state.activeNode =
findSiblingElement(state.nodes, oldIndex) || findSiblingElement(state.nodes, oldIndex, true);
}
if (document.activeElement === document.body) {
// if the focus got reverted to the body then the user was likely focused on the unmounted element
setTimeout(() => state.activeRef?.current?.focus(), 0);
setTimeout(() => state.activeNode?.focus(), 0);
}
}
// update the refs list
// update the nodes list
return { ...state };
}
case Type.SetFocus: {
// if the ref doesn't change just return the same object reference to skip a re-render
if (state.activeRef === action.payload.ref) return state;
// update active ref
state.activeRef = action.payload.ref;
// if the node doesn't change just return the same object reference to skip a re-render
if (state.activeNode === action.payload.node) return state;
// update active node
state.activeNode = action.payload.node;
return { ...state };
}
case Type.Update: {
state.refs.sort(refSorter);
state.nodes.sort(nodeSorter);
return { ...state };
}
@ -174,28 +175,28 @@ interface IProps {
}
export const findSiblingElement = (
refs: RefObject<HTMLElement>[],
nodes: HTMLElement[],
startIndex: number,
backwards = false,
loop = false,
): RefObject<HTMLElement> | undefined => {
): HTMLElement | undefined => {
if (backwards) {
for (let i = startIndex; i < refs.length && i >= 0; i--) {
if (refs[i].current?.offsetParent !== null) {
return refs[i];
for (let i = startIndex; i < nodes.length && i >= 0; i--) {
if (nodes[i]?.offsetParent !== null) {
return nodes[i];
}
}
if (loop) {
return findSiblingElement(refs.slice(startIndex + 1), refs.length - 1, true, false);
return findSiblingElement(nodes.slice(startIndex + 1), nodes.length - 1, true, false);
}
} else {
for (let i = startIndex; i < refs.length && i >= 0; i++) {
if (refs[i].current?.offsetParent !== null) {
return refs[i];
for (let i = startIndex; i < nodes.length && i >= 0; i++) {
if (nodes[i]?.offsetParent !== null) {
return nodes[i];
}
}
if (loop) {
return findSiblingElement(refs.slice(0, startIndex), 0, false, false);
return findSiblingElement(nodes.slice(0, startIndex), 0, false, false);
}
}
};
@ -211,7 +212,7 @@ export const RovingTabIndexProvider: React.FC<IProps> = ({
onKeyDown,
}) => {
const [state, dispatch] = useReducer<Reducer<IState, Action>>(reducer, {
refs: [],
nodes: [],
});
const context = useMemo<IContext>(() => ({ state, dispatch }), [state]);
@ -227,17 +228,17 @@ export const RovingTabIndexProvider: React.FC<IProps> = ({
let handled = false;
const action = getKeyBindingsManager().getAccessibilityAction(ev);
let focusRef: RefObject<HTMLElement> | undefined;
let focusNode: HTMLElement | undefined;
// Don't interfere with input default keydown behaviour
// but allow people to move focus from it with Tab.
if (!handleInputFields && checkInputableElement(ev.target as HTMLElement)) {
switch (action) {
case KeyBindingAction.Tab:
handled = true;
if (context.state.refs.length > 0) {
const idx = context.state.refs.indexOf(context.state.activeRef!);
focusRef = findSiblingElement(
context.state.refs,
if (context.state.nodes.length > 0) {
const idx = context.state.nodes.indexOf(context.state.activeNode!);
focusNode = findSiblingElement(
context.state.nodes,
idx + (ev.shiftKey ? -1 : 1),
ev.shiftKey,
);
@ -251,7 +252,7 @@ export const RovingTabIndexProvider: React.FC<IProps> = ({
if (handleHomeEnd) {
handled = true;
// move focus to first (visible) item
focusRef = findSiblingElement(context.state.refs, 0);
focusNode = findSiblingElement(context.state.nodes, 0);
}
break;
@ -259,7 +260,7 @@ export const RovingTabIndexProvider: React.FC<IProps> = ({
if (handleHomeEnd) {
handled = true;
// move focus to last (visible) item
focusRef = findSiblingElement(context.state.refs, context.state.refs.length - 1, true);
focusNode = findSiblingElement(context.state.nodes, context.state.nodes.length - 1, true);
}
break;
@ -270,9 +271,9 @@ export const RovingTabIndexProvider: React.FC<IProps> = ({
(action === KeyBindingAction.ArrowRight && handleLeftRight)
) {
handled = true;
if (context.state.refs.length > 0) {
const idx = context.state.refs.indexOf(context.state.activeRef!);
focusRef = findSiblingElement(context.state.refs, idx + 1, false, handleLoop);
if (context.state.nodes.length > 0) {
const idx = context.state.nodes.indexOf(context.state.activeNode!);
focusNode = findSiblingElement(context.state.nodes, idx + 1, false, handleLoop);
}
}
break;
@ -284,9 +285,9 @@ export const RovingTabIndexProvider: React.FC<IProps> = ({
(action === KeyBindingAction.ArrowLeft && handleLeftRight)
) {
handled = true;
if (context.state.refs.length > 0) {
const idx = context.state.refs.indexOf(context.state.activeRef!);
focusRef = findSiblingElement(context.state.refs, idx - 1, true, handleLoop);
if (context.state.nodes.length > 0) {
const idx = context.state.nodes.indexOf(context.state.activeNode!);
focusNode = findSiblingElement(context.state.nodes, idx - 1, true, handleLoop);
}
}
break;
@ -298,17 +299,17 @@ export const RovingTabIndexProvider: React.FC<IProps> = ({
ev.stopPropagation();
}
if (focusRef) {
focusRef.current?.focus();
if (focusNode) {
focusNode?.focus();
// programmatic focus doesn't fire the onFocus handler, so we must do the do ourselves
dispatch({
type: Type.SetFocus,
payload: {
ref: focusRef,
node: focusNode,
},
});
if (scrollIntoView) {
focusRef.current?.scrollIntoView(scrollIntoView);
focusNode?.scrollIntoView(scrollIntoView);
}
}
},
@ -337,46 +338,57 @@ export const RovingTabIndexProvider: React.FC<IProps> = ({
);
};
// Hook to register a roving tab index
// inputRef parameter specifies the ref to use
// onFocus should be called when the index gained focus in any manner
// isActive should be used to set tabIndex in a manner such as `tabIndex={isActive ? 0 : -1}`
// ref should be passed to a DOM node which will be used for DOM compareDocumentPosition
/**
* Hook to register a roving tab index.
*
* inputRef is an optional argument; when passed this ref points to the DOM element
* to which the callback ref is attached.
*
* Returns:
* onFocus should be called when the index gained focus in any manner.
* isActive should be used to set tabIndex in a manner such as `tabIndex={isActive ? 0 : -1}`.
* ref is a callback ref that should be passed to a DOM node which will be used for DOM compareDocumentPosition.
* nodeRef is a ref that points to the DOM element to which the ref mentioned above is attached.
*
* nodeRef = inputRef when inputRef argument is provided.
*/
export const useRovingTabIndex = <T extends HTMLElement>(
inputRef?: RefObject<T>,
): [FocusHandler, boolean, RefObject<T>] => {
): [FocusHandler, boolean, (node: T | null) => void, RefObject<T | null>] => {
const context = useContext(RovingTabIndexContext);
let ref = useRef<T>(null);
let nodeRef = useRef<T | null>(null);
if (inputRef) {
// if we are given a ref, use it instead of ours
ref = inputRef;
nodeRef = inputRef;
}
// setup (after refs)
useEffect(() => {
context.dispatch({
type: Type.Register,
payload: { ref },
});
// teardown
return () => {
const ref = useCallback((node: T | null) => {
if (node) {
nodeRef.current = node;
context.dispatch({
type: Type.Register,
payload: { node },
});
} else {
context.dispatch({
type: Type.Unregister,
payload: { ref },
payload: { node: nodeRef.current! },
});
};
nodeRef.current = null;
}
}, []); // eslint-disable-line react-hooks/exhaustive-deps
const onFocus = useCallback(() => {
context.dispatch({
type: Type.SetFocus,
payload: { ref },
payload: { node: nodeRef.current } as { node: T },
});
}, []); // eslint-disable-line react-hooks/exhaustive-deps
const isActive = context.state.activeRef === ref;
return [onFocus, isActive, ref];
const isActive = context.state.activeNode === nodeRef.current;
return [onFocus, isActive, ref, nodeRef];
};
// re-export the semantic helper components for simplicity

6
src/accessibility/roving/RovingTabIndexWrapper.tsx
View file

@ -13,7 +13,11 @@ import { FocusHandler, Ref } from "./types";
interface IProps {
inputRef?: Ref;
children(renderProps: { onFocus: FocusHandler; isActive: boolean; ref: Ref }): ReactElement<any, any>;
children(renderProps: {
onFocus: FocusHandler;
isActive: boolean;
ref: (node: HTMLElement | null) => void;
}): ReactElement<any, any>;
}
// Wrapper to allow use of useRovingTabIndex outside of React Functional Components.

112
test/unit-tests/accessibility/RovingTabIndex-test.tsx
View file

@ -28,6 +28,12 @@ const checkTabIndexes = (buttons: NodeListOf<HTMLElement>, expectations: number[
expect([...buttons].map((b) => b.tabIndex)).toStrictEqual(expectations);
};
const createButtonElement = (text: string): HTMLButtonElement => {
const button = document.createElement("button");
button.textContent = text;
return button;
};
// give the buttons keys for the fibre reconciler to not treat them all as the same
const button1 = <Button key={1}>a</Button>;
const button2 = <Button key={2}>b</Button>;
@ -123,11 +129,7 @@ describe("RovingTabIndex", () => {
{button2}
<RovingTabIndexWrapper>
{({ onFocus, isActive, ref }) => (
<button
onFocus={onFocus}
tabIndex={isActive ? 0 : -1}
ref={ref as React.RefObject<HTMLButtonElement>}
>
<button onFocus={onFocus} tabIndex={isActive ? 0 : -1} ref={ref}>
.
</button>
)}
@ -147,75 +149,75 @@ describe("RovingTabIndex", () => {
describe("reducer functions as expected", () => {
it("SetFocus works as expected", () => {
const ref1 = React.createRef<HTMLElement>();
const ref2 = React.createRef<HTMLElement>();
const node1 = createButtonElement("Button 1");
const node2 = createButtonElement("Button 2");
expect(
reducer(
{
activeRef: ref1,
refs: [ref1, ref2],
activeNode: node1,
nodes: [node1, node2],
},
{
type: Type.SetFocus,
payload: {
ref: ref2,
node: node2,
},
},
),
).toStrictEqual({
activeRef: ref2,
refs: [ref1, ref2],
activeNode: node2,
nodes: [node1, node2],
});
});
it("Unregister works as expected", () => {
const ref1 = React.createRef<HTMLElement>();
const ref2 = React.createRef<HTMLElement>();
const ref3 = React.createRef<HTMLElement>();
const ref4 = React.createRef<HTMLElement>();
const button1 = createButtonElement("Button 1");
const button2 = createButtonElement("Button 2");
const button3 = createButtonElement("Button 3");
const button4 = createButtonElement("Button 4");
let state: IState = {
refs: [ref1, ref2, ref3, ref4],
nodes: [button1, button2, button3, button4],
};
state = reducer(state, {
type: Type.Unregister,
payload: {
ref: ref2,
node: button2,
},
});
expect(state).toStrictEqual({
refs: [ref1, ref3, ref4],
nodes: [button1, button3, button4],
});
state = reducer(state, {
type: Type.Unregister,
payload: {
ref: ref3,
node: button3,
},
});
expect(state).toStrictEqual({
refs: [ref1, ref4],
nodes: [button1, button4],
});
state = reducer(state, {
type: Type.Unregister,
payload: {
ref: ref4,
node: button4,
},
});
expect(state).toStrictEqual({
refs: [ref1],
nodes: [button1],
});
state = reducer(state, {
type: Type.Unregister,
payload: {
ref: ref1,
node: button1,
},
});
expect(state).toStrictEqual({
refs: [],
nodes: [],
});
});
@ -235,122 +237,122 @@ describe("RovingTabIndex", () => {
);
let state: IState = {
refs: [],
nodes: [],
};
state = reducer(state, {
type: Type.Register,
payload: {
ref: ref1,
node: ref1.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref1,
refs: [ref1],
activeNode: ref1.current,
nodes: [ref1.current],
});
state = reducer(state, {
type: Type.Register,
payload: {
ref: ref2,
node: ref2.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref1,
refs: [ref1, ref2],
activeNode: ref1.current,
nodes: [ref1.current, ref2.current],
});
state = reducer(state, {
type: Type.Register,
payload: {
ref: ref3,
node: ref3.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref1,
refs: [ref1, ref2, ref3],
activeNode: ref1.current,
nodes: [ref1.current, ref2.current, ref3.current],
});
state = reducer(state, {
type: Type.Register,
payload: {
ref: ref4,
node: ref4.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref1,
refs: [ref1, ref2, ref3, ref4],
activeNode: ref1.current,
nodes: [ref1.current, ref2.current, ref3.current, ref4.current],
});
// test that the automatic focus switch works for unmounting
state = reducer(state, {
type: Type.SetFocus,
payload: {
ref: ref2,
node: ref2.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref2,
refs: [ref1, ref2, ref3, ref4],
activeNode: ref2.current,
nodes: [ref1.current, ref2.current, ref3.current, ref4.current],
});
state = reducer(state, {
type: Type.Unregister,
payload: {
ref: ref2,
node: ref2.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref3,
refs: [ref1, ref3, ref4],
activeNode: ref3.current,
nodes: [ref1.current, ref3.current, ref4.current],
});
// test that the insert into the middle works as expected
state = reducer(state, {
type: Type.Register,
payload: {
ref: ref2,
node: ref2.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref3,
refs: [ref1, ref2, ref3, ref4],
activeNode: ref3.current,
nodes: [ref1.current, ref2.current, ref3.current, ref4.current],
});
// test that insertion at the edges works
state = reducer(state, {
type: Type.Unregister,
payload: {
ref: ref1,
node: ref1.current!,
},
});
state = reducer(state, {
type: Type.Unregister,
payload: {
ref: ref4,
node: ref4.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref3,
refs: [ref2, ref3],
activeNode: ref3.current,
nodes: [ref2.current, ref3.current],
});
state = reducer(state, {
type: Type.Register,
payload: {
ref: ref1,
node: ref1.current!,
},
});
state = reducer(state, {
type: Type.Register,
payload: {
ref: ref4,
node: ref4.current!,
},
});
expect(state).toStrictEqual({
activeRef: ref3,
refs: [ref1, ref2, ref3, ref4],
activeNode: ref3.current,
nodes: [ref1.current, ref2.current, ref3.current, ref4.current],
});
});
});