tc39

proposal-iterator-helpers

HTML2019–2024

tc39 / proposal-iterator-helpers · Archived

proposal-iterator-helpers

Methods for working with iterators in ECMAScript

Web Development

Explore on GitHub Read Hacker News discussions

14Distinct people

19Mentions

0Explicit recommenders

1.3KGitHub stars

REPOSITORY AT A GLANCE

What to know before exploring

What it is

Methods for working with iterators in ECMAScript

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

tc39/proposal-slice-notation · linked in 3 of the same discussions

Mentioned in the same Hacker News threads. That is not proof they are substitutes.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 1:49:46 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year19 dated mentions

Observed mentions: 2019-04-09 00:36:01 UTC to 2024-11-04 19:35:37 UTC.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges

UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
Period	Start (UTC)	End (exclusive, UTC)	Mentions	Submissions	Comments
2019	2019-01-01 00:00:00 UTC	2020-01-01 00:00:00 UTC	3	0	3
2020	2020-01-01 00:00:00 UTC	2021-01-01 00:00:00 UTC	1	0	1
2021	2021-01-01 00:00:00 UTC	2022-01-01 00:00:00 UTC	4	2	2
2022	2022-01-01 00:00:00 UTC	2023-01-01 00:00:00 UTC	2	0	2
2023	2023-01-01 00:00:00 UTC	2024-01-01 00:00:00 UTC	5	0	5
2024	2024-01-01 00:00:00 UTC	2025-01-01 00:00:00 UTC	4	1	3

What Hacker News says

19 sources

WorldMaker·Nov 4, 2024

The versions of those methods (map/filter/reduce/etc) that support any iterator (including upgrading NodeList "for free") have passed Stage 4 of the process, which means they will be in the next version of the standard and already starting to show up in some browsers. https://github.com/tc39/proposal-iterator-helpers

In Cash: A small jQuery alternative for modern browsers

stefankuehnel·Oct 18, 2024Submission

TC39 Proposal: Iterator Helpers

1 points · Open discussion

ameliaquining·Aug 20, 2024

Many of these are at stage 3 of the standardization process and have a good chance of shipping soon: https://github.com/tc39/proposal-iterator-helpers (They're not on objects, which I think is probably for the best; every method on Object.prototype is a shadowing risk and so we're unlikely to see any besides the ones that already exist. You can always use Object.entries; if your object has so many dynamically-computed properties that eagerly collecting them is a performance concern, then it should probably be a Map.)

In JavaScript weakmaps should be iterable

jauntywundrkind·May 27, 2024

Shout out to JavaScript massively delaying https://github.com/tc39/proposal-async-iterator-helpers in the 23rd hour. The proposal seemed very close to getting shipped alongside https://github.com/tc39/proposal-iterator-helpers while basically accepting many of the constraints of current async iteration (one at a time consumption). But the folks really accepted that concurrency needs had evolved, decided to hold back & keep iterating & churning for better. I feel like a lot of the easy visible mood on the web (against the web) is that there's too much, that stuff is just piled in. But I see a lot of caring & deliberation & trying to get shit right & good. Sometimes that too can be maddening, but ultimately with the web there aren't really re-do-es & the deliberation is good.

In More Itertools

bakkoting·Dec 19, 2023

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.

In TC39: Add Object.groupBy and Map.groupBy

jauntywundrkind·Sep 16, 2023

Very much agreed. The amount of mileage we get from using Spread (literally the ...) alone has been amazing. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... Iteration helpers is shipping soon, that'll be a huge help (async iteration helpers will be delayed for a while). https://github.com/tc39/proposal-iterator-helpers . In the olden days, I feel like the codebases I worked on needed to use .apply() multiple times a week, to figure out some creative way of invoking functions. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... That's all gone now; I'd take even odds that 50% of my team knows .call and .apply. Chrome 117 is shipping Object.groupBy() and that's gonna be a huge help in eliminating a lot of the last places we end up using lodash. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

In Lodash just declared issue bankruptcy and closed every issue and open PR

bakkoting·Aug 24, 2023

There are now builtin iterator versions of most of these looped functions [1], should be shipping in stable Chrome next month. The "give me an array at the end" function is spelled toArray. But it's not going to help all that much with this problem. The iterator protocol in JS involves an allocation for every individual value, and while in some cases that can be optimized out, it's pretty tricky to completely optimize. It's always going to be difficult to beat a c-style for loop for performance. [1] https://github.com/tc39/proposal-iterator-helpers/

In Bun v0.8

HeavyFeather·Mar 9, 2023

> focus more on improving the terrible JS web API That's W3C’s job, not ECMA’s. > Where are all the containers? ? > Sorted sets/maps? Sets and Maps are sorted (by insertion order) > Why can't I even map an iterator? It's coming, but someone will likely be exhausted by that addition. https://github.com/tc39/proposal-iterator-helpers

In JavaScript and TypeScript features of the last 3 years

gherkinnn·Jan 2, 2023

As much as I like these concepts, I'd be hesitant about adding them to the language. At what point does a language support too many paradigms? In contrast, take the recently stage-3'd Iterator Helpers[0]. These build on top of the language by using methods that already exists in other parts. It feels natural and is more of the same. 0 - https://github.com/tc39/proposal-iterator-helpers#implementa...

In Functional Programming – How and Why

bakkoting·Nov 7, 2022

There's an active proposal which would let you do exactly that, going for stage 3 (ready for implementations) at the end of the month: https://github.com/tc39/proposal-iterator-helpers

In Why would anyone need JavaScript generator functions?

WorldMaker·Jul 28, 2022

> Switch statements JS has had switch statements for a long time. Do you mean switch "expressions" that can be used inline? It's not pretty but JS has long supported that too using either eval() "hacks" or IIFEs: https://stackoverflow.com/questions/32451049/is-eval-the-onl... Do you mean pattern matching? There are two Stage 1 TC39 proposals with different approaches to it: More hands-on/direct: https://github.com/tc39/proposal-pattern-matching More indirect: https://github.com/tc39/proposal-do-expressions > list comprehensions There are several libraries with strong Iterator support today that while not syntactically gorgeous do great jobs at allowing you to write simple list operations. Off the top of my head are IxJS and iter-tools, but also classic mainstays like up to date versions of lodash and Ramda. There's a Stage 2 proposal to b

Read the rest

ring more of them into "the standard library": https://github.com/tc39/proposal-iterator-helpers There's also a Stage 2 proposal for an operator to make the syntax generally nicer no matter the library: https://github.com/tc39/proposal-pipeline-operator > array slicing Array.prototype.slice() was added back in ES2015: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... Array.prototype.at() was "just added" in ES2022 for unary (single argument) "slice" (ability to use negative indexes): https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... If you prefer syntax to function calls, there's a Stage 1 proposal still live for that: https://github.com/tc39/proposal-slice-notation > better equality operators That ship has probably sailed. Most projects at this point just have linter rules to standardize everything to the more reliable "triple equals" (===, and !==). There are proposals for more structural equality functions in the standard library, though, for instance: https://github.com/tc39/proposal-array-equality

In HypeScript: Simplified TypeScript type system in TypeScript's own type system

Zababa·Dec 13, 2021

I often miss map, reduce and filter on iterators, though this is already a stage 2 proposal: https://github.com/tc39/proposal-iterator-helpers.

In Deno Joins TC39

lucacasonato·Dec 13, 2021

Mainly pushing proposals like https://github.com/tc39/proposal-iterator-helpers that make it easier to work with (async) iterators.

In Deno Joins TC39

tsujp·Jul 20, 2021Submission

JavaScript Iterator Helper Proposal

1 points · Open discussion

tosh·Jul 18, 2021Submission

Iterator Helpers

1 points · Open discussion

Showing the 15 most recent of 19 sources. Enable JavaScript to search and browse every indexed mention.