kai zhu kaizhu256 at
Sat Oct 7 03:59:35 UTC 2017

on tc39 criterias, this applies more to language-spec than library changes, but i think another criteria that can showstop stage 2-3 proposals is finding out whether a new syntax creates subtle engine de-optimizations that breaks the web.

around mid-2016, i recall sites like and using as their landing-page would frequently freeze and crash in chrome. each time, i basically could not use chrome to visit these sites for a week or so until chrome auto-updated. this issue may or may not be related to javascript, but it hardened my conservative-perspective on proposals that can negatively impact the web.

> On Oct 3, 2017, at 1:38 AM, Ben Newman <benjamin at> wrote:
> Taking a step back from the details of this proposal, I have some thoughts about why it seems to be struggling to find support.
> In no particular order, I would say this proposal
> relies on microbenchmarks, which can be misleading <>
> disregards Amdahl's Law <>, by pretending that real-world JS CPU usage is commonly/ever dominated by min/max computations
> replaces two O(n) loops with another O(n) loop that does slightly more work on each iteration, resulting in no complexity improvement, and a fairly modest (< 2x) constant factor improvement
> doesn't seem to provide usability/learnability improvements for any particular group of JS developers (for example, novice programmers)
> doesn't seem to prevent any common bugs in JS code
> As a member of TC39, I regret that we have not provided a clearer set of criteria for what it takes to get a new function into the standard library. While I can't speak for the committee as a whole, my suspicion is that this proposal is unlikely to meet that standard. It's a fine idea, but so are many other functions that you can implement in a normal (non-standard) library.
> I would also challenge the committee to think about (or link to!) any concrete written criteria that someone with an idea for a proposal could use to assess its chances of acceptance. Imagine how much time we could save!
> Ben
> On Mon, Oct 2, 2017 at 12:12 PM Xavier Stouder <xavier at <mailto:xavier at>> wrote:
> JDecker: Just added your solution on the benchmark, it beats every
> others solution and it's a elegant solution.
> Kai Zhu: We can't see the screenshot. But please take in consideration
> that it's been a long time that ECMAScript isn't only used in webapp,
> and that some of applications using it can eat more than a million
> numbers.
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