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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /resource-timing/304-response-recorded.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Resource Timing - cached resources generate performance entries</title>
<link rel="help"
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/entry-invariants.js"></script>
<script src="resources/resource-loaders.js"></script>
</head>
<body>
<h1>Description</h1>
<p>This test validates that a 304 Not Modified resource appears in the
Performance Timeline.</p>
<script>
// Need to fetch the same resource twice; the first will get a 200 response but
// the second request should be cached and get a 304.
promise_test(async () => {
performance.clearResourceTimings();
const unique = Math.random();
const path = `resources/fake_responses.py?tag=${unique}`;
await load.xhr_sync(path);
await load.xhr_sync(path, {"If-None-Match": `${unique}`});
const entries = await new Promise(resolve => {
const accumulator = [];
new PerformanceObserver(entry_list => {
entry_list.getEntries().forEach(entry => {
accumulator.push(entry);
});
if (accumulator.length >= 2) {
resolve(accumulator);
}
}).observe({'type': 'resource', 'buffered': true});
});
if (entries.length != 2) {
throw new Error(`Expecting 2 but got ${entries.length} entries`);
}
assert_equals(entries[0].name, entries[1].name,
"Both entries should have the same name");
invariants.assert_tao_pass_no_redirect_http(entries[0]);
invariants.assert_tao_pass_304_not_modified_http(entries[1]);
}, "304 responses should still show up in the PerformanceTimeline");
</script>
</body>
</html>