The static supportedEntryTypes read-only property of the PerformanceObserver interface returns an array of the entryType values supported by the user agent.

As the list of supported entries varies per browser and is evolving, this property allows web developers to check which are available.

An array of PerformanceEntry.entryType values.

To find out which entryType values a browser supports, enter PerformanceObserver.supportedEntryTypes into the console. This will return an array of supported values.

PerformanceObserver.supportedEntryTypes;

// returns ["element", "event", "first-input", "largest-contentful-paint", "layout-shift", "longtask", "mark", "measure", "navigation", "paint", "resource"] in Chrome 89

The following function checks for support of an array of possible entry types. The unsupported types are logged to the console, however this information could be logged to client-side analytics to indicate that the particular type could not be observed.

function detectSupport(entryTypes) {
  for (const entryType of entryTypes) {
    if (!PerformanceObserver.supportedEntryTypes.includes(entryType)) {
      console.log(entryType);
    }
  }
}

detectSupport(["resource", "mark", "first-input", "largest-contentful-paint"]);