@samitouri / QOS-React-2 / commits / 97cdd5d3c3

[eslint] Do not allow useEffectEvent fns to be called in arbitrary closures (#33544)

Summary: useEffectEvent is meant to be used specifically in combination with useEffect, and using the feature in arbitrary closures can lead to surprising reactivity semantics. In order to minimize risk in the experimental rollout, we are going to restrict its usage to being called directly inside an effect or another useEffectEvent, effectively enforcing the function coloring statically. Without an effect system this is the best we can do.

Jordan Brown committed Jul 10, 2025 at 16:51 UTC 97cdd5d3c33eda77be4f96a43f72d6916d3badbb

2 files changed +78 -70

packages/eslint-plugin-react-hooks/__tests__/ESLintRulesOfHooks-test.js

+56 -56

@@ -1343,33 +1343,6 @@ if (__EXPERIMENTAL__) {

1343 }

1344 `,

1345 },

1346 - {

1347 - code: normalizeIndent`

1348 - // Valid because functions created with useEffectEvent can be called in closures.

1349 - function MyComponent({ theme }) {

1350 - const onClick = useEffectEvent(() => {

1351 - showNotification(theme);

1352 - });

1353 - return <Child onClick={() => onClick()}></Child>;

1354 - }

1355 - `,

1356 - },

1357 - {

1358 - code: normalizeIndent`

1359 - // Valid because functions created with useEffectEvent can be called in closures.

1360 - function MyComponent({ theme }) {

1361 - const onClick = useEffectEvent(() => {

1362 - showNotification(theme);

1363 - });

1364 - const onClick2 = () => { onClick() };

1365 - const onClick3 = useCallback(() => onClick(), []);

1366 - return <>

1367 - <Child onClick={onClick2}></Child>

1368 - <Child onClick={onClick3}></Child>

1369 - </>;

1370 - }

1371 - `,

1372 - },

1346 {

1347 code: normalizeIndent`

1348 // Valid because functions created with useEffectEvent can be passed by reference in useEffect

@@ -1380,47 +1353,39 @@ if (__EXPERIMENTAL__) {

1353 });

1354 const onClick2 = useEffectEvent(() => {

1355 debounce(onClick);

1356 + debounce(() => onClick());

1357 + debounce(() => { onClick() });

1358 + deboucne(() => debounce(onClick));

1359 });

1360 useEffect(() => {

1385 - let id = setInterval(onClick, 100);

1361 + let id = setInterval(() => onClick(), 100);

1362 return () => clearInterval(onClick);

1363 }, []);

1388 - return <Child onClick={() => onClick2()} />

1364 + return null;

1365 }

1366 `,

1367 },

1392 - {

1393 - code: normalizeIndent`

1394 - const MyComponent = ({theme}) => {

1395 - const onClick = useEffectEvent(() => {

1396 - showNotification(theme);

1397 - });

1398 - return <Child onClick={() => onClick()}></Child>;

1399 - };

1400 - `,

1401 - },

1368 {

1369 code: normalizeIndent`

1370 function MyComponent({ theme }) {

1405 - const notificationService = useNotifications();

1406 - const showNotification = useEffectEvent((text) => {

1407 - notificationService.notify(theme, text);

1371 + useEffect(() => {

1372 + onClick();

1373 });

1409 - const onClick = useEffectEvent((text) => {

1410 - showNotification(text);

1374 + const onClick = useEffectEvent(() => {

1375 + showNotification(theme);

1376 });

1412 - return <Child onClick={(text) => onClick(text)} />

1377 }

1378 `,

1379 },

1380 {

1381 code: normalizeIndent`

1382 function MyComponent({ theme }) {

1419 - useEffect(() => {

1420 - onClick();

1383 + const onEvent = useEffectEvent((text) => {

1384 + console.log(text);

1385 });

1422 - const onClick = useEffectEvent(() => {

1423 - showNotification(theme);

1386 +

1387 + useEffect(() => {

1388 + onEvent('Hello world');

1389 });

1390 }

1391 `,

@@ -1437,7 +1402,7 @@ if (__EXPERIMENTAL__) {

1402 return <Child onClick={onClick}></Child>;

1403 }

1404 `,

1440 - errors: [useEffectEventError('onClick')],

1405 + errors: [useEffectEventError('onClick', false)],

1406 },

1407 {

1408 code: normalizeIndent`

@@ -1456,8 +1421,23 @@ if (__EXPERIMENTAL__) {

1421 });

1422 return <Child onClick={() => onClick()} />

1423 }

1424 +

1425 + // The useEffectEvent function shares an identifier name with the above

1426 + function MyLastComponent({theme}) {

1427 + const onClick = useEffectEvent(() => {

1428 + showNotification(theme)

1429 + });

1430 + useEffect(() => {

1431 + onClick(); // No error here, errors on all other uses

1432 + onClick;

1433 + })

1434 + return <Child />

1435 + }

1436 `,

1460 - errors: [{...useEffectEventError('onClick'), line: 7}],

1437 + errors: [

1438 + {...useEffectEventError('onClick', false), line: 7},

1439 + {...useEffectEventError('onClick', true), line: 15},

1440 + ],

1441 },

1442 {

1443 code: normalizeIndent`

@@ -1468,7 +1448,7 @@ if (__EXPERIMENTAL__) {

1448 return <Child onClick={onClick}></Child>;

1449 }

1450 `,

1471 - errors: [useEffectEventError('onClick')],

1451 + errors: [useEffectEventError('onClick', false)],

1452 },

1453 {

1454 code: normalizeIndent`

@@ -1481,7 +1461,7 @@ if (__EXPERIMENTAL__) {

1461 return <Bar onClick={foo} />

1462 }

1463 `,

1484 - errors: [{...useEffectEventError('onClick'), line: 7}],

1464 + errors: [{...useEffectEventError('onClick', false), line: 7}],

1465 },

1466 {

1467 code: normalizeIndent`

@@ -1497,7 +1477,27 @@ if (__EXPERIMENTAL__) {

1477 return <Child onClick={onClick} />

1478 }

1479 `,

1500 - errors: [useEffectEventError('onClick')],

1480 + errors: [useEffectEventError('onClick', false)],

1481 + },

1482 + {

1483 + code: normalizeIndent`

1484 + // Invalid because functions created with useEffectEvent cannot be called in arbitrary closures.

1485 + function MyComponent({ theme }) {

1486 + const onClick = useEffectEvent(() => {

1487 + showNotification(theme);

1488 + });

1489 + const onClick2 = () => { onClick() };

1490 + const onClick3 = useCallback(() => onClick(), []);

1491 + return <>

1492 + <Child onClick={onClick2}></Child>

1493 + <Child onClick={onClick3}></Child>

1494 + </>;

1495 + }

1496 + `,

1497 + errors: [

1498 + useEffectEventError('onClick', true),

1499 + useEffectEventError('onClick', true),

1500 + ],

1501 },

1502 ];

1503 }

@@ -1559,11 +1559,11 @@ function classError(hook) {

1559 };

1560 }

1561

1562 -function useEffectEventError(fn) {

1562 +function useEffectEventError(fn, called) {

1563 return {

1564 message:

1565 `\`${fn}\` is a function created with React Hook "useEffectEvent", and can only be called from ` +

1566 - 'the same component. They cannot be assigned to variables or passed down.',

1566 + `the same component.${called ? '' : ' They cannot be assigned to variables or passed down.'}`,

1567 };

1568 }

1569

packages/eslint-plugin-react-hooks/src/rules/RulesOfHooks.ts

+22 -14

@@ -541,7 +541,9 @@ const rule = {

541 context.report({

542 node: hook,

543 message:

544 - `React Hook "${getSourceCode().getText(hook)}" may be executed ` +

544 + `React Hook "${getSourceCode().getText(

545 + hook,

546 + )}" may be executed ` +

547 'more than once. Possibly because it is called in a loop. ' +

548 'React Hooks must be called in the exact same order in ' +

549 'every component render.',

@@ -596,7 +598,9 @@ const rule = {

598 ) {

599 // Custom message for hooks inside a class

600 const message =

599 - `React Hook "${getSourceCode().getText(hook)}" cannot be called ` +

601 + `React Hook "${getSourceCode().getText(

602 + hook,

603 + )}" cannot be called ` +

604 'in a class component. React Hooks must be called in a ' +

605 'React function component or a custom React Hook function.';

606 context.report({node: hook, message});

@@ -613,7 +617,9 @@ const rule = {

617 } else if (codePathNode.type === 'Program') {

618 // These are dangerous if you have inline requires enabled.

619 const message =

616 - `React Hook "${getSourceCode().getText(hook)}" cannot be called ` +

620 + `React Hook "${getSourceCode().getText(

621 + hook,

622 + )}" cannot be called ` +

623 'at the top level. React Hooks must be called in a ' +

624 'React function component or a custom React Hook function.';

625 context.report({node: hook, message});

@@ -626,7 +632,9 @@ const rule = {

632 // `use(...)` can be called in callbacks.

633 if (isSomewhereInsideComponentOrHook && !isUseIdentifier(hook)) {

634 const message =

629 - `React Hook "${getSourceCode().getText(hook)}" cannot be called ` +

635 + `React Hook "${getSourceCode().getText(

636 + hook,

637 + )}" cannot be called ` +

638 'inside a callback. React Hooks must be called in a ' +

639 'React function component or a custom React Hook function.';

640 context.report({node: hook, message});

@@ -681,18 +689,18 @@ const rule = {

689 Identifier(node) {

690 // This identifier resolves to a useEffectEvent function, but isn't being referenced in an

691 // effect or another event function. It isn't being called either.

684 - if (

685 - lastEffect == null &&

686 - useEffectEventFunctions.has(node) &&

687 - node.parent.type !== 'CallExpression'

688 - ) {

692 + if (lastEffect == null && useEffectEventFunctions.has(node)) {

693 + const message =

694 + `\`${getSourceCode().getText(

695 + node,

696 + )}\` is a function created with React Hook "useEffectEvent", and can only be called from ` +

697 + 'the same component.' +

698 + (node.parent.type === 'CallExpression'

699 + ? ''

700 + : ' They cannot be assigned to variables or passed down.');

701 context.report({

702 node,

691 - message:

692 - `\`${getSourceCode().getText(

693 - node,

694 - )}\` is a function created with React Hook "useEffectEvent", and can only be called from ` +

695 - 'the same component. They cannot be assigned to variables or passed down.',

703 + message,

704 });

705 }

706 },