Function callback

test/parallel/test-performanceobserver.js:66–71

(list, obs)

    new PerformanceObserver(common.mustCall(callback));

  function callback(list, obs) {
    assert.strictEqual(obs, observer);
    const entries = list.getEntries();
    assert.strictEqual(entries.length, 3);
    observer.disconnect();
  }
  observer.observe({ entryTypes: ['mark', 'node'] });
  performance.mark('test1');
  performance.mark('test2');