Event#timeStamp numbers are incorrect

[jaydenseric]

• Version: v15.12.0
• Platform: macOS v11.2.1 (Intel CPU)
• Subsystem: Events

What steps will reproduce the bug?

In demo.js:

console.log(new Event('a').timeStamp);

Then run:

node demo.js

How often does it reproduce? Is there a required condition?

Reproduces every time for me.

What is the expected behavior?

It should be a correct timestamp, e.g. 1616668905640.

What do you see instead?

The timestamp is a number way too small to be a timestamp, e.g. 29.311459064483643.

Additional information

Event#timeStamp docs on MDN.

[Ayase-252]

From given reference, Event.timeStamp is

This value is the number of milliseconds elapsed from the beginning of the current document's lifetime till the event was created.

rather than unix timestamp in milliseconds.

In Node, Event.timeStamp is the number of milliseconds elapsed from the start of the current node process, roughly equal to calling performance.now() when event creates.

Edit: grammar

[jaydenseric]

@Ayase-252 thanks, you're right. I've been bamboozled by legacy info. Implementations used to make it a unix timestamp, and some of the example values in places like MDN still are.

It should be possible to use performance.timeOrigin and an addition of the Event#timeStamp to get the unix timestamp of the event. In my situation, I actually didn't need that, in tests I just needed to subtract Event#timeStamp from performance.now() to assert that the event age in milliseconds is within an expected range.