Optimize arrayUnique

[kurkle]

uPlot (time: linear / data)
arrayUnique
70ms -> 15ms

[leeoniya]

Set would be more appropriate than Map, and the .has() check is unnecessary (and slower).

[kurkle]

Changed to Set. I guess using has could be faster if there are a lot of duplicates. There are only 3 of each timestamp in that uPlot case. No measurable difference either way in that case.

[leeoniya]

I guess using has could be faster if there are a lot of duplicates.

i dont see why that would be the case. Set must do this test internally in all cases either way. calling has() as a precondition to add() is never necessary or beneficial (i think).

[kurkle]

i dont see why that would be the case. Set must do this test internally in all cases either way. calling has() as a precondition to add() is never necessary or beneficial (i think).

You are probably right when talking about Set.
Map OTOH has to update the value too, which is relatively expensive.
jsperf

[benmccann]

Doing the has check seems slightly faster for Set as well: https://jsperf.com/chartjs-set-with-or-without-has

[kurkle]

Using spread instead of Array.from. Seems to be as fast.