Javascript Measure Runtime Performance Link to heading

You can use the performance API

const startTime = performance.now();
list.forEach(doExpensiveWork);
const endTime = performance.now() - startTime;

The time is in ms, to make it more human friendly:

function getElapsedTime(elapsedTime: number) {
  if (elapsedTime < 1000) {
    return `${elapsedTime.toFixed(3)} ms`;
  }
  if (elapsedTime < 60000) {
    return `${(elapsedTime / 1000).toFixed(2)} s`;
  }
  return `${(elapsedTime / 60000).toFixed(2)} m`;
}