.domInteractive read-only property returns an
unsigned long long representing the moment, in miliseconds since the UNIX epoch, when the parser finished its work on the main document, that is when its
Document.readyState changes to
'interactive' and the corresponding
readystatechange event is thrown.
This property can be used to measure the speed of loading Web sites that users feels. Nevertheless there are a few caveats that happens if scripts are blocking rendering and not loaded asynchronously or with custom Web fonts. Check if you are in one of these cases before using this property as a proxy for the user experience of a Web site's speed of loading.
time = performanceTiming.domInteractive;
The definition of 'PerformanceTiming.domInteractive' in that specification.