({ callback }: { callback: () => void })
| 430 | // Dummy component that we render as a child of Root so that we can |
| 431 | // toggle the correct styles before the page is rendered. |
| 432 | function Head({ callback }: { callback: () => void }): null { |
| 433 | // We use `useLayoutEffect` to guarantee the callback is executed |
| 434 | // as soon as React flushes the update. |
| 435 | React.useLayoutEffect(() => callback(), [callback]) |
| 436 | return null |
| 437 | } |
| 438 | |
| 439 | const performanceMarks = { |
| 440 | navigationStart: 'navigationStart', |
nothing calls this directly
no test coverage detected