Open met de inspector tools van je browser de console tab en plak de onderstaande code.
try { let cumulativeLayoutShiftScore = 0; const observer = new PerformanceObserver((list) => { for (const entry of list.getEntries()) { if (!entry.hadRecentInput) { cumulativeLayoutShiftScore += entry.value; } } }); observer.observe({ type: "layout-shift", buffered: true }); document.addEventListener("visibilitychange", () => { if (document.visibilityState === "hidden") { observer.takeRecords(); observer.disconnect(); console.log(`CLS: ${cumulativeLayoutShiftScore}`); } }); } catch (e) { console.log(`Browser doesn't support this API`); }