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[Fizz] Block on Suspensey Fonts during reveal #33342

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Merged
merged 1 commit into from
May 23, 2025
Merged

[Fizz] Block on Suspensey Fonts during reveal #33342

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2 changes: 1 addition & 1 deletion ...m-bindings/src/server/fizz-instruction-set/ReactDOMFizzInstructionSetInlineCodeStrings.js
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15 changes: 14 additions & 1 deletion ...es/react-dom-bindings/src/server/fizz-instruction-set/ReactDOMFizzInstructionSetShared.js
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,8 @@ const SUSPENSE_PENDING_START_DATA = '$?';
const SUSPENSE_QUEUED_START_DATA = '$~';
const SUSPENSE_FALLBACK_START_DATA = '$!';

const SUSPENSEY_FONT_TIMEOUT = 500;

// TODO: Symbols that are referenced outside this module use dynamic accessor
// notation instead of dot notation to prevent Closure's advanced compilation
// mode from renaming. We could use extern files instead, but I couldn't get it
Expand Down Expand Up @@ -251,7 +253,18 @@ export function revealCompletedBoundariesWithViewTransitions(
const transition = (document['__reactViewTransition'] = document[
'startViewTransition'
]({
update: revealBoundaries.bind(null, batch),
update: () => {
revealBoundaries(
batch,
// Force layout to trigger font loading, we pass the actual value to trick minifiers.
document.documentElement.clientHeight,
);
return Promise.race([
// Block on fonts finishing loading before revealing these boundaries.
document.fonts.ready,
new Promise(resolve => setTimeout(resolve, SUSPENSEY_FONT_TIMEOUT)),
]);
},
types: [], // TODO: Add a hard coded type for Suspense reveals.
}));
transition.ready.finally(() => {
Expand Down
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