Web Tips

How to check when a webpage was opened in your browser

Using the (deprecated) PerformanceTiming API:

console.log("The page was opened at:", new Date(performance.timing.navigationStart));

The modern approach uses PerformanceNavigationTiming:

const [navEntry] = performance.getEntriesByType("navigation");
if (navEntry) {
  console.log("The page was opened at:", new Date(navEntry.startTime + performance.timeOrigin));
}