Largest Contentful Paint (LCP)

The next scripts shows information about the LCP (opens in a new tab) metric.

You can use it in the browser console or as a snippet in the Chrome DevTools Source tab, take a look at the Introduction section.

Get the LCP element

List the Largest Contentful Paint in the console and add a green dotted line around the LCP element.

Snippet

const po = new PerformanceObserver((list) => {
  let entries = list.getEntries();
 
  entries = dedupe(entries, "startTime");
 
  entries.forEach((item, i) => {
    console.dir(item);
    console.log(
      `${i + 1} current LCP item : ${item.element}: ${item.startTime}`,
    );
    item.element ? (item.element.style = "border: 5px dotted lime;") : "";
  });
 
  const lastEntry = entries[entries.length - 1];
  console.log(`LCP is: ${lastEntry.startTime}`);
});
 
po.observe({ type: "largest-contentful-paint", buffered: true });
 
function dedupe(arr, key) {
  return [...new Map(arr.map((item) => [item[key], item])).values()];
}

CLS LCP Image Entropy