If the previous document and the current document have the same origin, the unloadEventEnd property must return the time immediately after the user agent finishes the unload event of the previous document. If there is no previous document or the previous document has a different origin than the current document, or the unload is not yet completed, this attribute must return zero.
An Integer value that represents the time immediately after the user agent finishes the unload event of the previous document.
- Navigation Timing, Section 4.2
The value reported by the unloadEventEnd property represents the number of milliseconds between the recorded time and midnight January 1, 1970 (UTC).
The following example shows how to calculate the time required to unload the previously loaded document from the window object.
var oTiming = window.performance.timing; var iTimeMS = oTiming.unloadEventEnd - oTiming.unloadEventStart;