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fix(tanstack-router): Check for fromLocation existence before reporting pageload #18463

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Merged
logaretm merged 2 commits into from
Dec 11, 2025
+48 −2
Merged

fix(tanstack-router): Check for fromLocation existence before reporting pageload #18463

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bf87914
fix: Check for existence before reporting pageload
logaretm Dec 10, 2025
c175152
test: added webvitals test
logaretm Dec 10, 2025
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41 changes: 41 additions & 0 deletions ...ackages/e2e-tests/test-applications/tanstack-router/tests/routing-instrumentation.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,47 @@ test('sends a pageload transaction with a parameterized URL', async ({ page }) =
});
});

test('sends pageload transaction with web vitals measurements', async ({ page }) => {
const transactionPromise = waitForTransaction('tanstack-router', async transactionEvent => {
return !!transactionEvent?.transaction && transactionEvent.contexts?.trace?.op === 'pageload';
});

await page.goto(`/`);

const transaction = await transactionPromise;

expect(transaction).toMatchObject({
contexts: {
trace: {
op: 'pageload',
origin: 'auto.pageload.react.tanstack_router',
},
},
transaction: '/',
transaction_info: {
source: 'route',
},
measurements: expect.objectContaining({
ttfb: expect.objectContaining({
value: expect.any(Number),
unit: 'millisecond',
}),
lcp: expect.objectContaining({
value: expect.any(Number),
unit: 'millisecond',
}),
fp: expect.objectContaining({
value: expect.any(Number),
unit: 'millisecond',
}),
fcp: expect.objectContaining({
value: expect.any(Number),
unit: 'millisecond',
}),
}),
});
});
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@cursor cursor bot Dec 10, 2025

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Bug: Test doesn't reproduce the regression being fixed (Bugbot Rules)

Per the review rules for fix PRs: the test should fail before the fix and pass after. The PR author explicitly states "I included a test anyways even though it doesn't reproduce it," meaning this test would have passed with the old buggy code. For proper regression testing, a test that specifically validates the condition where fromLocation is undefined during initial pageload and verifies no spurious navigation span is created would more directly test the fix.

Fix in Cursor Fix in Web


test('sends a navigation transaction with a parameterized URL', async ({ page }) => {
const pageloadTxnPromise = waitForTransaction('tanstack-router', async transactionEvent => {
return !!transactionEvent?.transaction && transactionEvent.contexts?.trace?.op === 'pageload';
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9 changes: 7 additions & 2 deletions packages/react/src/tanstackrouter.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -64,8 +64,13 @@ export function tanstackRouterBrowserTracingIntegration(
if (instrumentNavigation) {
// The onBeforeNavigate hook is called at the very beginning of a navigation and is only called once per navigation, even when the user is redirected
castRouterInstance.subscribe('onBeforeNavigate', onBeforeNavigateArgs => {
// onBeforeNavigate is called during pageloads. We can avoid creating navigation spans by comparing the states of the to and from arguments.
if (onBeforeNavigateArgs.toLocation.state === onBeforeNavigateArgs.fromLocation?.state) {
// onBeforeNavigate is called during pageloads. We can avoid creating navigation spans by:
// 1. Checking if there's no fromLocation (initial pageload)
// 2. Comparing the states of the to and from arguments
if (
!onBeforeNavigateArgs.fromLocation ||
onBeforeNavigateArgs.toLocation.state === onBeforeNavigateArgs.fromLocation.state
) {
return;
}

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