The read-only duration property returns a timestamp that is the duration of the performance entry. The meaning of this property depends on the value of this entry's entryType.

A DOMHighResTimeStamp representing the duration of the performance entry. If the duration concept doesn't apply for a particular performance metric, a duration of 0 is returned.

The meaning of this property depends on the value of this performance entry's entryType:

event

The time from the event's startTime to the next rendering paint (rounded to the nearest 8ms).

first-input

The time from the first input event's startTime to the next rendering paint (rounded to the nearest 8ms).

longtask

The elapsed time between the start and end of task, with a 1ms granularity.

measure

The duration of the measure.

navigation

The difference between the entry's loadEventEnd and startTime properties.

resource

The entry's responseEnd value minus the entry's startTime value.

For the following entry types, duration is not applicable, and in this case the value is always 0:

• element
• largest-contentful-paint
• layout-shift
• mark
• paint
• taskattribution
• visibility-state

The following example logs all observed performance entries with a duration larger than 0.

function perfObserver(list, observer) {
  list.getEntries().forEach((entry) => {
    if (entry.duration > 0) {
      console.log(`${entry.name}'s duration: ${entry.duration}`);
    }
  });
}
const observer = new PerformanceObserver(perfObserver);
observer.observe({ entryTypes: ["measure", "mark", "resource"] });