According to MDN, the KeyboardEventInit dictionary which is used to pass values to a new
instance of KeyboardEvent through its constructor new KeyboardEvent(init) includes the
which field as one of the allowed initialization values.
However, in testing with the following piece of JavaScript code, it becomes clear that this
does not actually set the which keyboard event property value:
new KeyboardEvent({ which: 190 }).which
This expression always evaluates to 0 which is the default for which if not provided,
so the code behaves as if which is not provided in the initialization dictionary.
Is it perhaps because which must be provided in conjunction with some other field of the
same dictionary?
LOL, turns out, yeah, there are implicit dependencies between the various fields of the
init dictionary as evidenced by the fact that when serializing all the enumerable fields
of an existing keyboard event and then initializing a new event off that dictionary, the
resulting even has a working which.
This makes sense, actually, it should be impossible to construct an event whose key says it is an Enter key but whose code or which say something different. But the JS API is, as is almost customary in the broader JS browser API ecosystem, absolute garbage. It could stand a more type-safe treatment, or at least should throw better (any!) errors, but it is too late for that by now. :-)