Chrome Dev tools .har file for _webSocketTraffic has a "time" field - what does it mean?

I am trying to understand the websocketTraffic data exported from my Chrome dev tools. An example looks like this:

{
    'type': 'receive',
    'time': 1640291138.212745,
    'opcode': 1,
    'data': '<r xmlns=\'urn:xmpp:sm:3\'/>',
  }

I see a "time" field but I actually cant find anything about what it means except this from the spec (http://www.softwareishard.com/blog/har-12-spec/):

time [number] - Total elapsed time of the request in milliseconds. This is the sum of all timings available in the timings object (i.e. not including -1 values) .

Is this really milliseconds, down to the millionth of a millisecond? I am trying to see how much time has elapsed between two WS events, so any insight would be very helpful. Thanks

Disclaimer:

This answer is not backed by official docs. However, I studied this problem for quite some time now, and my solution seems to make sense.

Answer:

Move the dot 3 places to the right, (i.e 1640291138.212745 -> 1640291138212.745) and you will get the actual time. Try to run this new Date(1640291138212.745).toISOString() and see if it fits your startedDateTime in the parent WebSocket entry in your har.

Probably Chrome saves the "time" field as seconds since epoch, instead of milliseconds since epoch. So "moving the dot 3 places to the right" actually means to multiply by a 1000 and that means converting to milliseconds.