Given your history I know better than to assume what you know… The definition of sparse in the spec (while not explicitly in its own section) is straightforward.
V8’s inability or unwillingness to perform a safe “upcast” internally to an appropriate tag doesn’t seem to provide enough weight to introduce a new construct. From: Andrea Giammarchi <[email protected]> Sent: Monday, February 10, 2020 2:26 PM To: Michael Haufe <[email protected]> Cc: Bergi <[email protected]>; [email protected] Subject: Re: Yet another attempt at typed JS data Great, now maybe you also read how it works behind the scene, and debug properly to understand that every array is holey, including the latter one, to date. https://v8.dev/blog/elements-kinds Please, let's assume for a second I knew what I was talking about, when I've said it's a mess to not have holey arrays, thanks. On Mon, Feb 10, 2020 at 9:21 PM Michael Haufe <[email protected]<mailto:[email protected]>> wrote: Array(3) // [empty × 3] Array(3).fill() // [undefined, undefined, undefined] Array(3).fill('whatever') // ["whatever", "whatever", "whatever"] -----Original Message----- From: es-discuss <[email protected]<mailto:[email protected]>> On Behalf Of Bergi Sent: Monday, February 10, 2020 1:27 PM To: [email protected]<mailto:[email protected]> Subject: Re: Yet another attempt at typed JS data Hello! > Unfortunately, `Array.from({ length: 4 }, () => whatever)` produces a > holey array Does it? But really, if the performance difference betweeen HOLEY and PACKED arrays were large enough to be relevant[1], the engine programmers would certainly already have optimised all those trivial cases where an array is filled gradually to produce the more efficient representation. kind regards, Bergi [1]: it probably isn't: https://stackoverflow.com/questions/54481918/#comment95848513_54485509 _______________________________________________ es-discuss mailing list [email protected]<mailto:[email protected]> https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [email protected]<mailto:[email protected]> https://mail.mozilla.org/listinfo/es-discuss
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