Time To First Byte

new PerformanceObserver((entryList) => {  const [pageNav] = entryList.getEntriesByType("navigation");  console.log(`TTFB (ms): ${pageNav.responseStart}`); }).observe({  type: "navigation",  buffered: true, });

new PerformanceObserver((entryList) => {  const entries = entryList.getEntries();  const resourcesLoaded = [...entries].map((entry) => {  let obj = {};  // Some resources may have a responseStart value of 0, due  // to the resource being cached, or a cross-origin resource  // being served without a Timing-Allow-Origin header set.  if (entry.responseStart > 0) {  obj = {  "TTFB (ms)": entry.responseStart,  Resource: entry.name,  };  }  return obj;  });  console.table(resourcesLoaded); }).observe({  type: "resource",  buffered: true, });