Met Chrome Console Largest Contentful Paint vinden

Open met de inspector tools van je browser de console tab en plak de onderstaande code. Het resultaat wordt met een blauwe stippellijn weergegeven in je browser.

/**
 * PerformanceObserver
 */
const po = new PerformanceObserver((list) => {
  let entries = list.getEntries();

  entries = dedupe(entries, "startTime");

  /**
   * Print all entries of LCP
   */
  entries.forEach((item, i) => {
    console.dir(item);
    console.log(
      `${i + 1} current LCP item : ${item.element}: ${item.startTime}`
    );
    /**
     * Highlight LCP elements on the page
     */
    item.element ? (item.element.style = "border: 5px dotted blue;") : "";
  });

  /**
   * LCP is the lastEntry in getEntries Array
   */
  const lastEntry = entries[entries.length - 1];
  /**
   * Print final LCP
   */
  console.log(`LCP is: ${lastEntry.startTime}`);
});

/**
 * Start observing for largest-contentful-paint
 * buffered true getEntries prior to this script execution
 */
po.observe({ type: "largest-contentful-paint", buffered: true });

function dedupe(arr, key) {
  return [...new Map(arr.map((item) => [item[key], item])).values()];
}