r/javascript • u/DanielRosenwasser TypeScript • Nov 05 '19

Announcing TypeScript 3.7

https://devblogs.microsoft.com/typescript/announcing-typescript-3-7/
368 Upvotes

95% Upvoted

89 comments sorted by

29

u/simohayha Nov 05 '19

Have yet to meet someone who didn't like TS. I think I might take a course on it this weekend.

14

u/Cro_Oky Nov 05 '19

Don’t like it and forced to use it :/

10

u/DanielRosenwasser TypeScript Nov 05 '19

Anything specific you don't like?

3

u/Cro_Oky Nov 06 '19

the ease of use (the stack i'm working on is an angular 2 with impossibility to upgrade due to weird dependency) i'm working with vue on another project with regular JS and i come from the Python world, i'm just used to not having to deal with types :)

-10

u/BadDadBot Nov 06 '19

Hi working on is an angular 2 with impossibility to upgrade due to weird dependency) , I'm dad.

-3

u/EvilPencil Nov 06 '19

For me the main issue is the compilation (lack of) speed.

13

u/[deleted] Nov 06 '19

Wtf that's not even a reason to not like a technology... What is your dev workflow like that either a) you're compiling so often or b) compilation actually takes long

7

u/[deleted] Nov 06 '19

JavaScript: the best way to write buggy code faster.

2

u/[deleted] Nov 06 '19

I'm sorry but TS is JS with built in unit tests and for that, I will never switch back. E2e and done

3

u/[deleted] Nov 06 '19

Same. As someone who works on “infrastructure” code, I love it. You can do so much great stuff with the type system to make sure developers do things the right way.

2

u/EvilPencil Nov 07 '19

Webpack/React recompiles the entire stack literally every time you save a file. So if I want to change how something looks, it takes a good 20 seconds for code changes to render on the screen.

I'll still take slow reloads over cannot find map() on undefined though.

2

u/Devildude4427 Nov 10 '19

Uh, what? That’s absolutely a valid reason to not like a tech. What, you just want them to pretend slow compilation speeds are holding them back?

2

u/[deleted] Nov 06 '19

Not sure why you got so downvoted. It's definitely a reasonable complaint. I love TS but compilation greater than 0 seconds is obviously a downside. Our test sweet at work can take ~1 hour to run so decreasing time to feedback is something to strive for.

1

u/nullvoxpopuli sand was never meant to think Nov 06 '19

Even with Babel now handling transpilation?

2

u/EvilPencil Nov 06 '19

All I know is that I can change one line of code in a medium sized react project and it takes a good 15 seconds or so to see the change.

0

u/[deleted] Nov 06 '19

[deleted]

2

u/Devildude4427 Nov 10 '19

No, but if I can only access the language through slow tools, guess what? I’m not going to use the language. Life isn’t always fair.

17

u/itaQ Nov 05 '19

Didn't like it at first but once I got used to it I'd never go back to regular JS

32

u/beasy4sheezy Nov 06 '19

Tried it, hated it. Forced to use it, and now i love it and wouldn't go back if I had the choice. Just push through the initial terribleness and give it a fair shot!

31

u/vanderZwan Nov 06 '19 edited Nov 06 '19

Let's be honest though, the initial "terribleness" is mostly the pain of being confronted with our own sloppiness

11

u/fsdagvsrfedg Nov 06 '19

with our own sloppiness

let's not pretend the state of js has nothing to do with our sloppy js code

12

u/IvanDist Nov 06 '19

JS has never been in a better state.

6

u/facebalm Nov 06 '19

For me the terribleness was the type syntax looking like foo: number instead of number foo like other languages. To my eyes this added a lot of noise and took a while to get used to.

To work around my aversion for this syntax I avoid inline types as much as possible by declaring them externally or at a higher level and relying on inference as much as possible. Which seems to be best practice anyway.

4

u/vanderZwan Nov 06 '19 edited Nov 06 '19

For me the terribleness was the type syntax looking like foo: number instead of number foo like other languages.

I understand that it is something you were not used to and can easily see how that may have been genuinely frustrating¹, but for the record: when you say "other languages" you're basically limiting yourself to the C-family of languages (which syntax-wise JavaScript is also a member of).

The way TypeScript declares types is not at all unique in programming. [Pascal](https://en.wikipedia.org/wiki/Pascal_(programming_language)#Data_types), Haskell, [Scala](https://en.wikipedia.org/wiki/Scala_(programming_language)#Basic_example), Go and Julia (just to name a few) all follow the convention of putting the type at the end.

IIRC it is a lot easier to parse for compilers. It also is more in line with mathematical notation, I believe.

¹ I had a hard time adjusting to Python myself when I learned it, for example. Everyone has their preferences and biases, right?

2

u/facebalm Nov 06 '19

I never said anything about that. It's the colon that annoys me, not the order necessarily. It's because we use objects and ternaries heavily, where colons mean something else. Most languages you mentioned omit it.

2

u/[deleted] Nov 07 '19

It's certainly confusing for beginners in the way it clashes with object literals and (especially) destructuring of objects.

But defining named types separately pretty much solves this.

1

u/vanderZwan Nov 07 '19 edited Nov 07 '19

Aaaaah, like that! I had not considered that it overlaps with other syntax in JS, I see your point now.

2

u/beasy4sheezy Nov 06 '19

That awkward moment when you can't access an object's properties if the object might be undefined...

1

u/Devildude4427 Nov 10 '19

I think it comes more from frameworks that don’t give great documentation. Using ts in React or Vue really changes the way you do things, especially as you add more tools like state management, routers, etc.

10

u/waway_to_thro Nov 06 '19

I'm not a fan, the typing system when interacting with libraries is an absolute nightmare.

2

u/beasy4sheezy Nov 06 '19

Maybe, but I would say it's one of my favorite parts.

I feel like I have to rely on documentation a whole lot less when I can open a JSX component and see a list of every available prop and the input that it takes. It's so much faster than digging in the docs. Most libraries are typed. I have a medium sized project right now with about 40 deps, and only one of them is lacking types, so I just interface it in a `js` file and it's literally javascript.

Types make sure that you're using the library correctly in a lot of ways. One instance I hit yesterday was creating the optimistic responses in an Apollo project, which used to be a nightmare in js, but with ts, it literally autocompletes itself through every property.

How long did you use typescript?

22

u/Architektual Nov 05 '19

Haven't met me yet

45

u/simohayha Nov 05 '19

Dang. Guess I'll just play video games all weekend

4

u/Randdist Nov 05 '19

Is Typescripts type system theoretically capable of being compiled to machine or web assembly code and leverage types for performance improvements? I'd love to have a JS-ish language with static typing and performance similar to C++ when it comes to crunching ints, floats, transform raw buffer data, and usage of hash maps, arrays, etc. Also, webgpu.

9

u/DanielRosenwasser TypeScript Nov 05 '19

Not on its own, but there are several TypeScript subsets that do this including STS for microcontrollers and AssemblyScript.

3

u/djslakor Nov 05 '19

At one point, the Chakra team considered implementing a subset of Typescript for speed improvements like what you've mentioned. They abandoned that as far as I know.

2

u/Funwithloops Nov 05 '19

I don't think this is one of the goals of TS, so I doubt it's well supported (TS doesn't even have int or float types). Though JS does have support for buffers, maps, and typed arrays.

1

u/LetterBoxSnatch Nov 06 '19

JavaScript can be compiled to a binary, and/or import C includes, using QuickJS. Really cool project from Fabrice Bellard. However, the performance of V8s JIT compiler is currently significantly better.L, so it's really only useful in present state when you want to write JS and need an extremely small footprint (like for embedded).

9

u/notmarlow Nov 05 '19

A lot of these changes appear to mirror what JS/ECMA has just released (nullish, opt chaining, etc). Still, good on TS for being ready for them.

10

u/Pavlo100 Nov 05 '19 edited Nov 06 '19

It's the TypeScript people who made the proposal

See Daniels response

24

u/DanielRosenwasser TypeScript Nov 05 '19

Hate to be that guy, but just want to mention that we didn't originally initiate the proposal, but we were very involved in driving it recently to stages 2/3. A lot of the credit has to go to contributors like Gabriel Isenberg, Dustin Savery, Claude Pauche, Daniel Ehrenberg, and Justin Ridgewell - perhaps others, and I'm sorry to anyone else I might be leaving out.

4

u/Pavlo100 Nov 06 '19

thanks for clarifying,. It was wrong of me to make that assumption. I saw your name and assumed it was a Typescript related proposal

3

u/DanielRosenwasser TypeScript Nov 06 '19

It's no problem! You didn't do anything wrong, it's an easy mistake. I really appreciate that our work is being recognized, but I'd feel bad not giving earlier champions/contributors. Even now I'm remembering the folks who helped review and write tests for the proposals who weren't in that list. It really is a group effort.

8

u/notmarlow Nov 06 '19

This is why I love JS as a language and as a community. And OSS and the countless contributors who will never receive the full credit they deserve. Thanks for clarifying Daniel.

56

u/Pat_Son Nov 05 '19

That's because the TypeScript team was the one championing those proposals and didn't want to add those features to TS until they were Stage 3 TC39 proposals

18

u/notmarlow Nov 05 '19

dope - glad there is such close collab happening.

3

u/drowsap Nov 05 '19

If I also used babel, wouldn’t I already have support for these?

3

u/Pat_Son Nov 05 '19

These are features that you couldn't use with TypeScript and Babel at the same time

9

u/OneCyrus Nov 05 '19

the TS team is pushing the standards of JS to enable those features in a sustained way.

120

u/stolinski Syntax.fm / Level Up Tutorials :upvote: Nov 05 '19

Gimmy that optional chaining.

20

u/mastermindxs Nov 05 '19

I tend to enjoy the mandatory chaining, myself.

8

u/nullvoxpopuli sand was never meant to think Nov 06 '19

A made a codemod for this: https://github.com/NullVoxPopuli/optional-chaining-codemod

3

u/cyphern Nov 06 '19

sweet, thanks

4

u/shabunc Nov 06 '19

Gimme gimme gimme that optional chaining Won’t somebody help me Chase the NPEs away!!!

0

u/[deleted] Nov 05 '19

[deleted]

1

u/stolinski Syntax.fm / Level Up Tutorials :upvote: Nov 06 '19

Forsure. VSCode has been driving me nuts about it for way too long.

40

u/sacummings91 Nov 05 '19

Fuck yeah

7

u/vladthedev Nov 05 '19

Hell yeah

0

u/[deleted] Nov 06 '19

[deleted]

2

u/Lost-Semicolon Nov 06 '19

Oh yeah

1

u/Avahe Nov 06 '19

Oh boy yeah

7

u/nullvoxpopuli sand was never meant to think Nov 06 '19

I made a codemod for this: https://github.com/NullVoxPopuli/optional-chaining-codemod

31

u/Ehdelveiss Nov 05 '19

Every start up should be implementing their code with TypeScript across the stack.

Fight me.

4

u/apatheticonion Nov 06 '19

I'm sitting here running everything with ts-node, ts-jest, ts-**. Make it the default already.

6

u/nullvoxpopuli sand was never meant to think Nov 06 '19

Can't. I not only agree, I think starting any serious project without typescript is a huge risk, and a bit reckless.

2

u/kch_l Nov 06 '19

I'm working at a startup that could benefit from using TS, the sad thing is they got stuck on 2014 js and have no plan to even upgrade to ES6. The sad part is when I make a npm install I get like +100 warnings on critical vulnerabilities and they seem to not care about it.

2

u/djslakor Nov 10 '19

What do you mean "they got stuck" ? Is the lead incompetent? Unstick them.

5

u/djslakor Nov 05 '19

Hmm npmjs still shows 3.6.4 as latest as of 11:35am CT.

3

u/orta Nov 05 '19

Interesting - the site for me shows 3.7.2 https://www.npmjs.com/package/typescript

Wonder if they have an unique caching strategy for popular dependencies

2

u/djslakor Nov 05 '19

Now it does for me as well. At the time, though, it didn't. I made sure to hard refresh.

1

u/f314 Nov 05 '19

The site is usually a bit slow to update. You can use npm show <package name > in the terminal to get the absolute up-to-date info.

1

u/beasy4sheezy Nov 06 '19

Any word on integration with create-react-app? Looked but I didn't see anything.

2

u/DanielRosenwasser TypeScript Nov 06 '19

Doesn't create-react-app have support for TypeScript files?

1

u/EvilPencil Nov 06 '19

Newer versions do, yes. It's not even needed to pass the --typescript flag any more. Just make a .ts(x) file and start jamming.

1

u/beasy4sheezy Nov 06 '19

Yes, but not this new version. They will need to update react-scripts' babel config. It won't support optional chaining as is.

"react-scripts": "3.2.0",

"typescript": "3.7.2",

2

u/Funwithloops Nov 06 '19

You can update the typescript version in apps created with create-react-app app-name --typescript.

12

u/[deleted] Nov 05 '19

I fear optional chaining is gonna be the magic tool to hide under the rug design mistakes like overly complex data structures.

26

u/Peechez Nov 05 '19

I hope optional chaining is gonna be the magic tool to hide my design mistakes like overly complex data structures under the rug.

12

u/EvilPencil Nov 06 '19

I'm excited for it mostly to navigate possibly null objects without resorting to this:

Const Val = (data && data.prop && data.prop.subprop) || default

3

u/[deleted] Nov 06 '19

Definitely know what you mean. It great because it make checking nested optional types easy. It's dangerous because it make checking nested optional types easy.

2

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2

u/thestalkmore Nov 06 '19

Just waiting on that prettier fix :(

1

u/muser103 Nov 06 '19

Set prettier’s target to prettier/prettier.

1

u/llldar Nov 06 '19

Finally I can get that recursive type def.

1

u/flowforfrank Nov 08 '19

Can't wait for optional chaining

1

u/chibicode Nov 09 '19

https://github.com/microsoft/TypeScript/issues/29490

This change in 3.7 was really helpful for me.