Change Event.timeStamp to be a DOMHighResTimeStamp which is a high resolution monotonic time with microseconds resolution instead DOMTimeStamp which is an epoch time with millisecond resolution. For input events, the timestamp value will represent the underlying OS timestamp for the event. High resolution monotonic timestamp for input events enables new functionality such as accurate measurement of pointer velocity, simple input latency measurements, and etc.
Docs: https://github.com/whatwg/dom/issues/23 https://lists.w3.org/Archives/Public/public-whatwg-archive/2014May/0055.html
Samples: https://googlechrome.github.io/samples/event-timestamp/index.html http://rbyers.net/scroll-latency.html