9 NEW JavaScript Features in ES2025

In this video CJ shows the 9 new features that made it into JavaScript from the ES2025 spec.

00:00 intro
00:35 ECMAScript Versions
02:51 Set Methods
06:43 RegExp Pattern Modifiers
07:50 RegExp Duplicate Named Capture Groups
08:55 Import Attributes / JSON Modules
11:06 Iterator Helpers
13:40 Float16Array
14:48 Thanks!

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[N.A._]

so stoked about the Set methods!
Everytime they add something that reduces the amount of unnecessary array creations in JS land, I get happier

[CossuttaDario]

Float16Array : JS by default stores any number within an array in a 64 bit format( also called "word"). Float32Array isn't an attempt to have bigger numbers in JS, but to reduce memory footprint with precision as a tradeoff (see binary representation of numbers). Float16Array are a further step in that direction. Their use boils down to how many meaningful digits do you need in that "set of numbers".

[BogdanDeaconescu]

Really appreciate these videos, especially the concise and practical approach, CJ! It's refreshing how thoughtful and to-the-point you are. Makes everything so much easier to understand. Keep it up 👍

[LaSanya]

A year ago I started a little project for work, and I tried to import mock data from a json file and I was so frustrated that there was no super fast and easy method that didn't feel like a hack. Glad to see that I might not have to do that anymore!

[noriller]

The iterators one are really cool. Generators are a niche solution to some problems, but this... this will make things a lot smoother.
If you stream, you can parse and transform the stream of data before the whole request finished. With these helpers... it's even better and easier.
Now I want some proposal for streaming helpers for fetch.

[Khaltazar-]

Oh, I really like the import of JSON into JS, you can do that still today, but this is much cleaner and looks less like a 'hack'!

[Typed-Rocks]

Great video. Love to see the new features. Especially the new Set methods added. Now it can finally be implemented in the runtime. 🎉

[alvingultiano]

i like your channel bro, you have different way to delivery the content unlike to other devs

[oliver_peng]

Iterator Helpers have been really nice! Now we can iterate directly on things like Maps: without having to allocate an array first:

[prashlovessamosa]

I hope we get signals in future updates.

[justafreakable]

Man, all the newbies are running after AI and Coding agent. And here some of us are still learning new things the traditional way.

[sovereignlivingsoul]

excellent video, the user access control and toArray are interesting, not sure but the toArray may get me out of a conundrum i am currently facing, take care and God Bless

[MichaelRichins]

Import Attributes are a game changer! Especially if you are going to create HTML Custom Elements. I cannot wait until the HTML and CSS assertions are added across the board!!!

[raph]

I feel that the new Set methods can be a great help, but I disagree that they are simpler of more readable, the main advantage is the potential performance gain by moving JS code to the native realm. JS engines can now attempt to optimize their implementations. Before the engine would have to recognize patterns, and since there are many ways to achieve some of the common operations, formalizing them within a limited subset makes it way easier to optimize at the JIT level, mainly because common operation will now be funneled into these functions. Many use case will remain outside the bounds so it's not replacing all the possible set/array operation. I don't mean that the new function are less readable, but the JS code that they replace is extremely easy to read. If some complex algorithms were added as Set method, than yes it would make them more readable, but it's not the case here.

[JeremyDawesJezweb]

So does that mean the style sheets are inside of a single JavaScript object so you don’t need all of the separate link or declarations of the CSS in the header? 10:31

[ragtop]

Is there a function to help reduce those hard S's in your mic audio? Maybe drop it down by a few decibels at 16K-20K?
All joking aside, very useful info 👍

[sanampakuwal]

Some of the features seems inspired by C# LINQ?

[mrlectus]

When they're gonna make it possible to use generators with arrow functions?

[TheUnknownFactor]

Im not yet using any of these. I would've liked a `with: { type: "raw" }`; that I would've used in the past week. However I'm looking at those set functions and wondering if I should finally start using Sets

[harrydparkes]

Bro really said that a 32-bit float is a "really big number" despite it being half the size of a JavaScript `number` object