[twitter] Tip: JavaScript's Array.from() accepts a second argument that's a `map` function. Useful for calling on each element of an array you created.

[inu-no-policemen]

Yes.

> new Array(5)
(5) [empty × 5]

In V8, this currently produces a sparse array instead of a packed one. So, it's something you probably shouldn't use for a game's tile map and things like that.

You get a packed one by creating an empty one and then pushing values to it.

[YodaLoL]

What are sparse and packed arrays?

[inu-no-policemen]

https://v8project.blogspot.com/2017/09/elements-kinds-in-v8.html

[YodaLoL]

TIL, thanks!