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Listen to onScroll during hydration #19803

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106 changes: 106 additions & 0 deletions packages/react-dom/src/__tests__/ReactDOMEventListener-test.js
Original file line number Diff line number Diff line change
Expand Up @@ -12,11 +12,13 @@
describe('ReactDOMEventListener', () => {
let React;
let ReactDOM;
let ReactDOMServer;

beforeEach(() => {
jest.resetModules();
React = require('react');
ReactDOM = require('react-dom');
ReactDOMServer = require('react-dom/server');
});

describe('Propagation', () => {
Expand Down Expand Up @@ -797,4 +799,108 @@ describe('ReactDOMEventListener', () => {
document.body.removeChild(container);
}
});

it('should subscribe to scroll during updates', () => {
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This wasn't failing previously but I added for completeness.

const container = document.createElement('div');
const ref = React.createRef();
const log = [];
const onScroll = jest.fn(e =>
log.push(['bubble', e.currentTarget.className]),
);
const onScrollCapture = jest.fn(e =>
log.push(['capture', e.currentTarget.className]),
);
document.body.appendChild(container);
try {
ReactDOM.render(
<div>
<div>
<div />
</div>
</div>,
container,
);
ReactDOM.render(
<div
className="grand"
onScroll={onScroll}
onScrollCapture={onScrollCapture}>
<div
className="parent"
onScroll={onScroll}
onScrollCapture={onScrollCapture}>
<div
className="child"
onScroll={onScroll}
onScrollCapture={onScrollCapture}
ref={ref}
/>
</div>
</div>,
container,
);
ref.current.dispatchEvent(
new Event('scroll', {
bubbles: false,
}),
);
expect(log).toEqual([
['capture', 'grand'],
['capture', 'parent'],
['capture', 'child'],
['bubble', 'child'],
]);
} finally {
document.body.removeChild(container);
}
});

// Regression test.
it('should subscribe to scroll during hydration', () => {
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This one fails on master with the eager flag, but passes here.

const container = document.createElement('div');
const ref = React.createRef();
const log = [];
const onScroll = jest.fn(e =>
log.push(['bubble', e.currentTarget.className]),
);
const onScrollCapture = jest.fn(e =>
log.push(['capture', e.currentTarget.className]),
);
const tree = (
<div
className="grand"
onScroll={onScroll}
onScrollCapture={onScrollCapture}>
<div
className="parent"
onScroll={onScroll}
onScrollCapture={onScrollCapture}>
<div
className="child"
onScroll={onScroll}
onScrollCapture={onScrollCapture}
ref={ref}
/>
</div>
</div>
);
document.body.appendChild(container);
try {
container.innerHTML = ReactDOMServer.renderToString(tree);
ReactDOM.hydrate(tree, container);
ref.current.dispatchEvent(
new Event('scroll', {
bubbles: false,
}),
);
expect(log).toEqual([
['capture', 'grand'],
['capture', 'parent'],
['capture', 'child'],
['bubble', 'child'],
]);
} finally {
document.body.removeChild(container);
}
});
});
2 changes: 2 additions & 0 deletions packages/react-dom/src/client/ReactDOMComponent.js
Original file line number Diff line number Diff line change
Expand Up @@ -1086,6 +1086,8 @@ export function diffHydratedProperties(
}
if (!enableEagerRootListeners) {
ensureListeningTo(rootContainerElement, propKey, domElement);
} else if (propKey === 'onScroll') {
listenToNonDelegatedEvent('scroll', domElement);
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The fix. This mirrors similar branches in two other places in this file.

}
}
} else if (
Expand Down