timeStamp property missing from Event & CustomEvent

[aripalo]

Is your feature request related to a problem? Please describe.

Event (and hence CustomEvent) are missing the timeStamp property. This means that for example unit tests running with happy-dom will fail if they try to access the undefined timeStamp property.

Example code:

console.debug("TYPEOF timeStamp", typeof event.timeStamp);

TYPEOF timeStamp undefined

Describe the solution you'd like
Happy DOM should assign the timeStamp property.

(I will be providing a pull request.) I've provided a Pull Request for this at #723

Describe alternatives you've considered

• Hack my own tests to check if timeStamp is undefined – basically making the tests useless
• Override the global CustomEvent – feels dirty

Additional context

Looking at jsdom implementation of timeStamp is just a Date.now() – which does not match the specification (see MDN and Spec):

This value is the number of milliseconds elapsed from the beginning of the time origin until the event was created. If the global object is Window, the time origin is the moment the user clicked on the link, or the script that initiated the loading of the document. In a worker, the time origin is the moment of creation of the worker.

I think we could do better: My proposed solution is to use performance.timeOrigin as the time origin to resolve the relative Event timeStamp value.