LongTasks EQT estimator

longtasks-eqt.js

let longTaskObserver, beginTime, endTime;
let taskDurations = [];
function begin() {
  longTaskObserver = new PerformanceObserver(function(entryList) {
    const entries = entryList.getEntries();
    for (let i = 0; i < entries.length; i++) {
      taskDurations.push(entries[i].duration);
    }
  });
  beginTime = performance.now();
  longTaskObserver.observe({entryTypes: ['longtask']});
}

let result = 0;
function end() {
  longTaskObserver.disconnect();
  endTime = performance.now();
  for (let i = 0; i < taskDurations.length; i++) {
    result += (taskDurations[i] * taskDurations[i]) / (2*(endTime - beginTime));
  }
}