proposal-array-grouping VS proposal-change-array-by-copy

Global iterator type is coming: https://github.com/tc39/proposal-iterator-helpers

But a method named `groupBy` on iterators traditionally means a different thing: https://github.com/tc39/proposal-array-grouping/issues/51#is...

Global iterable type it's too late for, since there's many extant iterables in the language and on the web which don't have it in their prototype chain and can't reasonably be changed.

Array grouping to combine like data into groups using Object.groupBy() and Map.groupBy().

Array Grouping: A proposal to make grouping of array items easier.

They are coming out with array.group() soon, which is supposed to also fulfil the use-case of partitioning :) - https://github.com/tc39/proposal-array-grouping.

https://github.com/tc39/proposal-array-grouping for those curious

I'm also looking forward to map.emplace() and arr.group() and iterator helpers.

At the end of the day, it comes down to whether browser vendors are willing to ship the feature even though it breaks said websites, and they do have visitor data to back those decisions. If the rule was "never break any website ever", you'd be able to block proposals you don't personally like by crafting a website that "gets broken" by that proposal.

At least in the array grouping proposal, they did evaluate amount and popularity of possibly breaking sites, before eventually renaming the method from .groupBy to .group

https://github.com/tc39/proposal-array-grouping/issues/37

The proposal is described here.

Remarkably, this is now a TC39 proposal.

Proposal, Polyfill

The new change array by copy methods (ES2023) will also work with tuples. So while you can't

Change Array by Copy

Stage 3 Change array by copy proposal offers methods like sortTo() that return a new array instead of mutating the original.

Note: there's a stage 3 proposal that introduces copy = arr.toSorted().

Change Array by Copy: Provides additional methods on Array.prototype and TypedArray.prototype to enable changes on the array by returning a new copy of it with the change.

The proposal is described here, with the other methods being:

Proposal, Polyfill

You're unlikely to see any new methods being added to JavaScript's Array that would modify an array in place like reverse() and sort() do. In fact some of the new methods that are being added are versions of reverse() and sort() (and splice()) that create copies rather than modifying the originals. Read more about them here: Proposal: Change Array by copy.

Since cloning is so common, a new specification has been written which has reached stage 3, which will give us a host of new ways to copy and then change an array. This proposal is called the "Change Array by Copy" proposal. Let's take a look at how it works.