TS to JSDoc Conversion

https://github.com/sveltejs/svelte/pull/8569

by ajhenrydev • 3 years ago

222 157 3 years ago

Why would anyone do this?

rcme3• 3 years ago

As a Svelte compiler developer, debugging without a build step greatly simplifies compiler development. Previously, debugging was complicated by the fact that we had to debug using the build step. In addition, using JSDoc does not affect compiler’s development safety because the type is almost equivalent to TS.
Of course, Svelte developers (not compiler developers) will still be provided type definition files as now, so there will be no change for Svelte developers in terms of typing.

Someone who maintains the JS debugger for VS Code added this (in response to a Svelte developers saying they couldn't use a faster compiler due to debugging difficulty):

It's an aside from the main PR, but I'm not entirely sure what you mean here. This should not exclude the ability to use alternative TS compilers--in fact, the js debugger itself is built with esbuild. The debugger should also handle runtime transpilers (like tsx) just fine.

yid• 3 years ago

ts-node [1]: am i a joke to you?

[1] https://www.npmjs.com/package/ts-node

maxloh2• 3 years ago

Why don't them just use `tsc --watch`?

djbusby• 3 years ago

To keep the benefits of Types w/o the burden of TS.

merb• 3 years ago

with the difference that typescript generates the types automatically or at least tries to and in JSDoc the user needs to write the JSDoc.

Edit, btw: Most complex types in the MR are now completly broken. It's crazy that there is a serious project out there who tries to mix jsdoc and typescript interfaces in the same project. it's like getting bad things from two worlds.

mxkyb3• 3 years ago

In general, your code is still valid JavaScript and can run in any browser or node environment. Typescript probably is not going to disappear, but if it would, your code wouldn‘t have to change. And you don’t loose your types, because the typescript compiler can interpret jsdoc as if you were using typescript directly.

_0w8t2• 3 years ago

10 years ago I have used Closure compiler from Google, https://github.com/google/closure-compiler/wiki/Annotating-T... , as a type checker. We had to use for production a different minimizer, not the closure compiler, but it was extremely useful to check for types and JSDoc-style annotations were very readable with minimal distraction.

Flow for JS from Facebook also supports types-as-comments, https://flow.org/en/docs/types/comments/ , but those are rather ugly as one has to intermix them with JS rather than using separated comment block on top.

ajhenrydev• 3 years ago

Twitter thread about it https://twitter.com/puruvjdev/status/1655813548495486977

nickreese• 3 years ago

Used to be really active in the svelte community and developed my own framework that got broad use. Getting Svelte and TS working together was a constant battle. This is a good decision.

benmccann2• 3 years ago

Svelte will still provide type definitions. We're working on Svelte 4 currently and are taking the opportunity to make a few small breaking changes to the type definitions for improved TypeScript support: https://github.com/sveltejs/svelte/blob/version-4/CHANGELOG....

We'll cut a preview release soon and would love help testing and feedback from folks that have given it a try.

ilrwbwrkhv• 3 years ago

yes this is much better. to be able to reach the actual source code which makes a function run is something we have all lost with so many layers in the middle.

gred• 3 years ago

It always makes me chuckle when a bunch of non-contributors come out of the woodwork to provide their opinion on a change which will affect them not at all.

inglor• 3 years ago

Funnily enough it's always stuff that's bikesheddding.

I spend months trying to solicit feedback on new experimental stremaing/cancellation APIs in Node and it's silence for a year until people start using it.

We say that contributors agreed to list pronouns in the readme or we mention inclusivity and oh-boy do a lot of random people from the internet cares about how the volunteers that write the software they use for free refer to each other internally.

cjohnson318• 3 years ago

oh-boy do a lot of random people from the internet cares about how the volunteers that write the software they use for free refer to each other internally

Oh boy. If they don't like it, then they don't have to contribute. (Spoiler: none of them are contributing anything.)

EGreg• 3 years ago

We also demand that they stop working on any web3 integrations because it’s useless and we dont like it

rcme3• 3 years ago

I think the reason is that the change just sounds so insane at face value that many can't help but comment on it.

lucasyvas• 3 years ago

Isn't casting with JSDoc impossibly ugly though? The inputs/outputs of a function signature are not the only times a type annotation is needed in TS.

mirekrusin2• 3 years ago

Type imports are the worst.

dTP90pN• 3 years ago

Do you mean native JSDoc namepaths like

    /**
     * @type {module:look/here~MyType}
     */

or TypeScript "JSDoc" imports like

    /**
    * @type {typeof import("./look/here").MyType}
    */

or both?

eyelidlessness3• 3 years ago

Type casting (type assertion, in TS parlance) is incredibly annoying to do in JS/JSDoc. In an ideal world, that would be a distinct advantage because type assertions are typically, or at least should be, considered risky: it’s a brute force way to ignore type errors. In the real world, you might find you have to correct inferred types, sometimes because they’re naively wide (eg, so many DOM interfaces devolve from HTMLElement to Element for no obvious reason!), but also often because they’re overly narrow (eg, so many dynamic collection member accesses completely ignore null safety, again for no obvious reason).

In practice, what I’ve found is that the hassle of adding type assertions even if they’re correct nudges me to write worse code (“to appease the type checker”) in JS/Doc than it does in TypeScript syntax. I don’t think TypeScript syntax makes me feel more relaxed about writing unsafe type assertions, but I’m probably an outlier because I pretty much only do that when I’ve exhausted every other available/known approach.

givemeethekeys• 3 years ago

A bit off-topic (sorry):

Is anyone using Svelte in production without SvelteKit?

Hows Svelte documentation as of late?

TehShrike3• 3 years ago

I've been using Svelte in production without SvelteKit for around 5 years now. The docs have always been pretty great in my opinion

arzke• 3 years ago

Is there any reason you wouldn't want to use SvelteKit now that is has reached version 1.0?

wirahx• 3 years ago

Yep, but slowly converting it all over to SvelteKit. Saves me having to maintain servers, watch setups, build processes, deployment processes, routing, bundling, and so on.

sanitycheck• 3 years ago

Yes, because Kit won't work on my target platforms.

They've been focusing on SvelteKit, so plain Svelte has stayed pretty much the same for a while. It's nice, stable, feels finished. I'm ever so slightly afraid of what could happen now attention appears to be on it again.

The docs + tutorial are very good, even approaching "fun" (YMMV).

alserio• 3 years ago

iep, doing csr microfrontends

rcarr8• 3 years ago

If I remember right, symfony (php framework) has comments that affect how the code runs which as far as I’m concerned means they’re not comments at all but actually code masquerading as comments. Reading about JSDoc gives me the same uneasy feeling, even if it’s not quite the same thing.

Edit:

Here’s one example, you can define your routes in symfony using comments. Not only that, but it’s actually the officially recommended way of doing things. Absolute madness.

https://symfony.com/doc/current/routing.html

kamikaz1k• 3 years ago

where does it say that JSDoc has runtime implications?

rcarr8• 3 years ago

It doesn’t and I say in my comment that it is not the same thing. Nevertheless it gives me the same uneasy feeling because you don’t know what features are going to creep into the language further down the road.

leoedin• 3 years ago

Are they not using attributes, which start with a #? I thought PHP had C style // comments.

jjice4• 3 years ago

They are attributes. PHP does also allow # as a comment character in addition to // style comments and I assume that's where the poster got confused.

supriyo-biswas• 3 years ago

That’s a PHP attribute:

https://php.watch/articles/php-attributes

jjice4• 3 years ago

I don't see any comments there, I see attributes though [1]. Is that what you meant?

From the page you linked:

Routes can be configured in YAML, XML, PHP or using attributes. All formats provide the same features and performance, so choose your favorite. Symfony recommends attributes because it's convenient to put the route and controller in the same place.

Attributes are not comments, they are an official structured way of handling metadata.

[1] https://www.php.net/manual/en/language.attributes.overview.p...

rcarr8• 3 years ago

I’m sorry, but if it’s using the same starting symbol as a comment, and it’s greyed out in the text editor like a comment, then you can call it whatever you want, but it is a fucking comment. There are a bunch of unused symbol combinations on the keyboard that could have been used, there is absolutely no excuse for it.

hiccuphippo• 3 years ago

Attributes are a newish thing in Php that got created because people were using comments as code. And yeah, before attributes Symfony would use comments to define routes right above the function definition.

masklinn2• 3 years ago

as I’m concerned means they’re not comments at all

Smuggling pragmas in comment has a long and rich history. It’s literally the reason why json does not support comments.

Reading about JSDoc gives me the same uneasy feeling, even if it’s not quite the same thing.

It’s not just “not quite the same thing”, it’s entirely unrelated in every way and shape. JSDoc does not affect the runtime behaviour of its code, or how that code interacts with other systems.

rcarr8• 3 years ago

JSDoc does not affect the runtime behaviour of its code, or how that code interacts with other systems.

At the moment. You’ve literally just said yourself that there is a long history of smuggling code into comments. A few years down the line I don’t want to suddenly have the feature added and then have to be on the look out when I’m debugging a codebase for secret code in comments.

apocalyptic0n3• 3 years ago

JSDoc's PHP equivalent is phpDoc. It's just a way to document things and both are third party libraries that have industry-wide adoption.

What you're thinking of in PHP is not a comment. It's called an Attribute, is built into PHP itself, and while it does use a comment-syntax, it's the old style that is largely unused today ("#" at the start of a line). https://www.php.net/manual/en/language.attributes.overview.p...

JSDoc isn't similar at all, unless you build a compiler that does different things based on your JSDocs.

philo23• 3 years ago

Originally Symfony did use comments (docblock style ones like: /* @Route ... */) for this kind of thing, but since PHP 8 they've moved towards using attributes [1]. The syntax of the attributes #[Route(...)] might look like a comment, but they are actually just valid bits of code you can pragmatically inspect through reflection [2] and then choose to run if you want.

Docblock comments can also be inspected with reflection [3] but have a much looser syntax, so it was up to you to parse them. Where as you can create a new instance of an attribute directly from the reflection object [4]

In your example Symfony uses it to build up the list of HTTP routes by looking through all your controllers for #[Route] attributes. Generally that's done once and then cached, at least in production.

Personally I try to avoid using them, but they're definitely not comments. More like metadata you can attach to classes/methods/properties/parameters then use however you want.

[1] https://www.php.net/manual/en/language.attributes.syntax.php

[2] https://www.php.net/manual/en/reflectionclass.getattributes....

[3] https://www.php.net/manual/en/reflectionclass.getdoccomment....

[4] https://www.php.net/manual/en/reflectionattribute.newinstanc...

rcarr8• 3 years ago

might look like a comment, but they are actually just valid bits of code

So comments that are code then.

Everyone can sit around going “This is not a pipe it’s a photo of a pipe or my perception of a photo of a pipe”. But if you did not have a sentence above your photo saying “This is not a pipe” or an arts teacher to tell you “this is not a pipe” and there was just a picture of a pipe on the page and someone pointed at it and said “can you tell me what that is?” You would say “why of course, it’s a pipe”. And then all of a sudden it started spouting water out of the end (let’s assume it was a GIF) then you can say “oh it looks like a pipe but it’s actually a water pistol masquerading as a pipe”. The fact that as a dev you have to constantly be on the look out for water pistols masquerading as pipes rather than having a clear distinction between pipes and water pistols is just a piss poor and easily avoidable design decision.

https://en.m.wikipedia.org/wiki/The_Treachery_of_Images

brundolf2• 3 years ago

has comments that affect how the code runs
Reading about JSDoc gives me the same uneasy feeling, even if it’s not quite the same thing

The key difference with TypeScript is that even "real" TypeScript types never ever affect runtime behavior, they are purely descriptive. This is an explicit goal of the project (and they've had to make some compromises in other areas to uphold it), so I don't see it ever changing

protonimitate• 3 years ago

For those that didn't read the thread - this is for the Svelte compiler, not the Svelte library. Users of Svelte will be unaffected and typedefs will still be available.

_oyks3• 3 years ago

For anyone who is still confused - they're still gonna be using TypeScript in that they will have a tsconfig.json, `allowJS: true, checkJS: true` but they are just writing the files in JS with JSDoc type annotations, they'll still have `.d.ts` files to allow TS developers to use it without issues.

Is it contrarian - yes - is it insane - no, not really.

Edit: the motivation seems to be to simplify processes - running TS files can be awkward, and cross importing is awkward. fwiw created my own tool for this ([url-redacted])

echeese• 3 years ago

TS can generate d.ts files from JS files that use JSDoc

_oyks3• 3 years ago

ty, updated

rkeene2• 3 years ago

I argue that it should support the other direction as well (.ts to .js with JSDoc instead of .ts to .js+.d.ts), but the TypeScript devs said they do not support that

hn_throwaway_993• 3 years ago

but they are just writing the files in JS with JSDoc type annotations

I think this is the critical piece not everyone understands. Under the covers, it's basically still Typescript (see https://www.typescriptlang.org/docs/handbook/intro-to-js-ts....). The major difference is that type information is specified in comments so that the source file is still valid JS and thus doesn't need a separate compilation step. There is not an exact parity between type info that can be specified with JSDoc and Typescript, but my understanding is that it's pretty close.

Any folks familiar with Flow (before Typescript essentially won out), Flow had something similar that was very nice, IMO better because it was the same Flow syntax, just wrapped in comments: https://flow.org/en/docs/types/comments/

skrebbel• 3 years ago

XNR looks nice! I’m impressed that it can be faster than esbuild-runner, is there a downside?

_oyks3• 3 years ago

I know why it's fast (it doesn't do anything it doesn't need to), but not exactly sure why it's faster than esbuild-runner; presumably it had a higher latency when tested.

(and downsides not really, beyond it's pretty fresh so bug reports welcome)

maxloh2• 3 years ago

What is the reason behind choosing sucrase over swc?

FYI, you committed the wrong license file. The license file contains license text of a standard MIT License, but your project is licensed under Apache...

gureddio• 3 years ago

It really doesn't look like that big of a change as well. Looking at the PR, they didn't go too heavy on their typescipt usage. I can see they when using typescript, they added types for function parameters, but not for return types, for example.

dobladov• 3 years ago

We do this at my current company for all projects, it does not mean you don't use typescript, you will still validate all your files with TS, but there's no build step, just a check.

Very rarely we find a case that we can't cover with JSDoc annotations, and most of the time it means the code could be refactored to be simpler.

I do this now for all my personal projects, in my opinion it's simpler, faster and closer to pure JS.

makapuf• 3 years ago

This is great but -if I dare - wouldn't it be time to allow js to have type annotations [1] ? As in python, treat it as comments for now but with real syntax and let interesting dialects emerge from the consensus ? I like jsdoc but the syntax is urgh.

[1] https://github.com/tc39/proposal-type-annotations

herpdyderp• 3 years ago

It will be impossibly exciting if that proposal happens. I hate build steps, one of the reasons I latched onto JS for my career, but TS is just so good that I had to go full blast with it after using it for the first time.

Tade03• 3 years ago

Very rarely we find a case that we can't cover with JSDoc annotations

I regret every `infer` statement I've put in application code.

Grug phrased this elegantly:

https://grugbrain.dev/#grug-on-type-systems

ripplefringe• 3 years ago

I have never seen grug before. This is fantastic.

paulddraper• 3 years ago

TS compiler should have an CLI option to compile without type checks.

TS features don't need types to produce output[1] and this is supported by the compiler; it just doesn't have a CLI option.

Compiling without types is supported the compiler itself (this is what Babel does).

[1] Except const enum and export *

Rapzid2• 3 years ago

It's really VERY easy to use something like esbuild or SWC though and just use TS for doing checks on the side. SWC would have ripped the TS annotations out of the top 100 TS projects on GitHub before I even finished typing this sentence.

alerighi• 3 years ago

Very rarely we find a case that we can't cover with JSDoc annotations, and most of the time it means the code could be refactored to be simpler.

Can with JSDoc define types? And can you define generic types? To me that is the real power of TypeScript, being able to type every object you use.

mjjp• 3 years ago

Yes you can with @typedef and @template

mxkyb3• 3 years ago

and you can always define more complex types in interfaces and import into jsdoc.

MrJohz• 3 years ago

What your build/deployment steps without the Typescript syntax? Do you bundle or minify at all, or do you release your source files directly? Or is this mostly for NodeJS/server side stuff?

I ask because for most of my projects there's at least some bundling going on, and in that case the added complexity of Typescript compilation is pretty minimal - with tools like Vite there is no added complexity, because JS and TS files are going down exactly the same pipeline, parsed by the same parser, etc. And I could get rid of the bundler, which would make some things simpler, but makes imports and deployment more complicated. For the scale of projects that I'm working on, bundling feels like necessary complexity.

I guess I'm trying to figure out if this is a useful form of minimalism for the sorts of projects I work on, or if this is the sort of thing that works for some projects but not others.

fenomas• 3 years ago

I've been doing the same for years and I'm really happy with it.

But the one big annoyance is events - I've never found a satisfying way of writing a JSdoc that says what events a class emits, or what parameters the events have. Do you have a way of handling this?

brainzap• 3 years ago

How do you type class properties?

https://github.com/microsoft/TypeScript/issues/26811

porsager• 3 years ago

Finally things are heading in the right direction. Can't wait for more to do this. Typescript might be good for some, but I'm glad to see the hype finally begin to fade, so the rest of up can breathe again.

18al• 3 years ago

The biggest hurdle to using TypeScript is the build step before it can actually be run. If the type annotation TC39 [0] comes to pass this would be largely taken care of; _hype_ waxes. (unfortunately the proposal has been stagnant for more than a year now)

A lot of the new frontend codebases involve a build step before running. For such codebases, TypeScript's build hurdle has already been overcome.

[0] https://github.com/tc39/proposal-type-annotations

joduplessis• 3 years ago

I love pure JS over TS any day, but isn't this using JSDoc in a way it's not meant to be used? Why would you use JSDoc as a JS type framework? Or is the post title a bit misleading...?

gizmo• 3 years ago

Because this way you get amazing IDE support with code navigation, refactoring, and (with strict mode) warnings about likely bugs and missing null checks.

phpnode• 3 years ago

this is exactly what JSDoc is for, it's had these capabilities from the start.

nepeckman• 3 years ago

The developers providing everyone with free tools are or course welcome to write those tools in whatever languages they want. But to me, the comment definitions are longer to type and more difficult to parse than inline type definitions. I would much rather use one of the quick TS compilers that don't actually type check when I want to make and test a small change to my source code. But to each their own!

cxr2• 3 years ago

If a person value- TypeScript's inline syntax so much that they disagree with the developers that build steps are a nuisance, then surely they can put in a build step for themselves—one that takes TypeScript syntax as input and then "compiles" it into the equivalent JSDoc so they're never forced to type out those long, long comments. (If this is disagreeable, then your position is a lot less consistent than you think.)

sdwvit• 3 years ago

JSDoc and Typescript don't have feature parity: OOP that works across files, generics, inline types, etc.

rich_harris4• 3 years ago

This is a non-issue in practice — complex types can be expressed in .d.ts files and imported. SvelteKit (not Svelte) has been doing this for a long time and it's fine.

zdragnar• 3 years ago

I wish this were true. I'm currently dealing with three third-party libraries whose types are out of date with the actual code because they do this.

eyelidlessness3• 3 years ago

It’s usually a non issue for most normal use cases. Some exceptions are truly maddening though, if you have good reason to use them. One off the top of my head that personally peeved me enough to ragequit one of my side projects: you cannot, as far as I’m aware, define an interface and assign its type to a class (neither its static constructor nor its instance members), without redeclaring every single member type in JSDoc. You can’t (again as far as I’m aware) even define types adjacent to their project-local implementation module and treat them the same way as @types/typeRoots. Both of these would be solvable if you could <reference …/> without polluting global scope, but again that’s a behavior only (again as far as I’m aware) available to dependencies.

I’d be thrilled to make the concession to a TypeScript flavor of header/implementation file pairs and skip a build step for huge portions of my work. But I spent way too long trying to figure out how to do it and my only remaining hope that it’s even possible is to wait for the “you don’t know?!” replies. (If it’s not clear here, they’d be very very welcome!)

Zamicol3• 3 years ago

We are (unfortunately) already doing just JSDoc.

Typescript migration was on our road map, but when we dug into it, it didn't solve the biggest issue we had with Javascript, which forces the developer to be aware of various pitfalls. Because of that, we didn't feel that TypeScript solved enough of JavaScript's faults to warrant a migration.

I still think that TypeScript is great and has some of the best tooling I've had the pleasure of working with, but in our case we didn't feel that the added complexity was worth the trade off. JSDoc is "good enough", even though we've run into bugs with it on VS Code.

rcme3• 3 years ago

What kind of pitfalls are you talking about?

Zamicol3• 3 years ago

Digs through some of my Javascript Twitter rants

The latest I ran into, `Object.keys(x).length` appears to recalculate length on every call. There doesn't appear to be a fast (and idiomatic) way to get top level object size in Javascript without using a secondary incrementor.

progx• 3 years ago

Sveltekit, back to server side rendering.

Documentation, with JSDoc back to good old comment/type documentation.

Can't wait to see what clock we set the time back at next.

bilalq3• 3 years ago

It's immediately clear from the very first few lines of the PR that they're sacrificing safety for this.

Before:

    import { Node } from 'acorn';
    import * as code_red from 'code-red';

    export const parse = (source: string): Node =>
      code_red.parse(source, {
        sourceType: 'module',
        ecmaVersion: 13,
        locations: true
      });

After:

    import * as code_red from 'code-red';

    /**
     * @param {string} source
     * @returns {any}
     */
    export const parse = (source) =>
      code_red.parse(source, {
        sourceType: 'module',
        ecmaVersion: 13,
        locations: true
      });

But I'm not a Svelte maintainer or user, so if this is their choice, I guess it is what it is. It's not something I'd ever consider. There are other approaches for making linked npm package workflows more manageable. There's the one mentioned by one of the VSCode maintainer, but the simplest setup is to just have a watch process running that recompiles on the fly.

rich_harris4• 3 years ago

You are making judgements based on a draft PR. There is a ton of work still to do.

bilalq3• 3 years ago

Fair enough! I'd love to read a blog post about this after you finish the work.

EDIT: It'd be a great outcome in the end if this conversion spurs DX improvements in Node/TS.

Rapzid2• 3 years ago

There is a ton of work still to do.

What's the estimated ROI?

myvoiceismypass• 3 years ago

Maybe I am unfamiliar with jsdoc, or what the shape of Node from acorn is, but yeah if every function is returning any, that seems like a big downgrade and sacrifice.

_gruntled3• 3 years ago

We're using an automated tool to do the gross conversion, then combing through fixing the issues. There's a reason the PR's a draft, dammit! :lol: Don't worry, _no_ type-safety will be lost, internally or externally.

bilalq3• 3 years ago

Fair enough. Minor nit, the PR is not actually marked as a draft.

zoogeny• 3 years ago

A decent expanded explanation of why in this YouTube video: https://www.youtube.com/watch?v=MJHO6FSioPI&ab_channel=Svelt...

rich_harris4• 3 years ago

Lordy, I did not expect an internal refactoring PR to end up #1 on Hacker News. Let me provide some context, since a lot of people make a lot of assumptions whenever this stuff comes up!

If you're rabidly anti-TypeScript and think that us doing this vindicates your position, I'm about to disappoint you. If you're rabidly pro-TypeScript and think we're a bunch of luddite numpties, I'm about to disappoint you as well.

Firstly: we are not abandoning type safety or anything daft like that — we're just moving type declarations from .ts files to .js files with JSDoc annotations. As a user of Svelte, this won't affect your ability to use TypeScript with Svelte at all — functions exported from Svelte will still have all the same benefits of TypeScript that you're used to (typechecking, intellisense, inline documentation etc). Our commitment to TypeScript is stronger than ever (for an example of this, see https://svelte.dev/blog/zero-config-type-safety).

I _would_ say that this will result in no changes that are observable to users of the framework, but that's not quite true — it will result in smaller packages (no need to ship giant sourcemaps etc), and you'll be able to e.g. debug the framework by cmd-clicking on functions you import from `svelte` and its subpackages (instead of taking you to an unhelpful type declaration, it will take you to the actual source, which you'll be able to edit right inside `node_modules` to see changes happen). I expect this to lower the bar to contributing to the framework quite substantially, since you'll no longer need to a) figure out how to link the repo, b) run our build process in watch mode, and c) understand the mapping between source and dist code in order to see changes.

So this will ultimately benefit our users and contributors. But it will also benefit _us_, since we're often testing changes to the source code against sandbox projects, and this workflow is drastically nicer than dealing with build steps. We also eliminate an entire class of annoying papercuts that will be familiar to anyone who has worked with the uneven landscape of TypeScript tooling. The downside is that writing types in JSDoc isn't quite as nice as writing in TypeScript. It's a relatively small price to pay (though opinions on this do differ among the team - this is a regular source of lively debate).

We're doing this for practical reasons, not ideological ones — we've been building SvelteKit (as opposed to Svelte) this way for a long time and it's been miraculous for productivity.

benmccann2• 3 years ago

I was skeptical at first when we made the change in SvelteKit. However, SvelteKit has a large integration test suite and being able to change the code and rerun the tests against the real final version of the code without waiting for any build step to complete has been a big improvement to productivity and I'm now a big fan of having made the change there. The tradeoff may be a bit different in Svelte core where we have more unit tests and fewer integration tests, so we're still investigating and considering the change, but we do have experience with both approaches and at the end of the day great software can be built using either approach.

preommr• 3 years ago

Lordy, I did not expect an internal refactoring PR to end up #1 on Hacker News. Let me provide some context, since a lot of people make a lot of assumptions whenever this stuff comes up!

Because people want to follow in the footsteps of big projects that have gained specialized knowledge through experience.

It's also a really contrarian viewpoint about typescript which is really popular.

tbh, this seems pretty far out there. Sourcemap file size is a non-issue, they're not gigabytes, and editors like vscode now support going to the source definition for projects that support it. To completely switch over to js and then set types that way seems regressive. Just so that people can modify the source code directly a little bit easier? There are all kinds of tools ranging from ts-node-dev that make watching typescript files easy, with options to skip type checking for better speed. Honestly seems kind of backwards.

capableweb2• 3 years ago

tbh, this seems pretty far out there. Sourcemap file size is a non-issue, they're not gigabytes

Sure, by themselves, but replicate that across everyone repeatedly downloading the library in various build processess, in various projects and with different versions.

Sure, by itself a sourcemap might not add up to much. But then there is various projects with different versions, who download the library repeatedly in different build steps. Then it starts to add up both in bandwidth, and in storage taken.

Luckily, there are still package and library maintainers who care about making things less, instead of more, both in architectures and size.

Just so that people can modify the source code directly a little bit easier?

This is a real thing that is useful to think about, how to make your software easier to change in the future, while just solving the current concern without over-engineering the solution.

_gruntled3• 3 years ago

It's also a really contrarian viewpoint about typescript which is really popular.

I really, really don't get the controversy here. JSDoc _is_ TypeScript, just with a syntax that's valid JavaScript (on account of it living in comments). This means it doesn't have to be built to run, but still gets all of the typing goodies regular TypeScript does. The end-user code authoring experience is the same or better.

To completely switch over to js and then set types that way seems regressive.

"It's regressive to use a fully-JS TypeScript syntax instead of using dozens of tools on top of regular TypeScript to achieve the same outcome" is quite a spicy take.

javajosh• 3 years ago

Great move, Rich! It's quite enjoyable working without sourcemaps.

I'll add that IntelliJ+Copilot makes writing solid JSDoc very fast and easy.

PaulMest• 3 years ago

I don't use Svelte, but I appreciate the principled approach and the clear explanation.

I primarily coded in Python for 4 years. Then I founded a company that didn't need as much data science and my primary language switched to JavaScript (2 years) then TypeScript (4 years). Overall, I really like TypeScript. But I do absolutely miss being able to cmd + click into a function/class from an open source package and see the actual implementation and not just a type definition. This is probably the biggest day-to-day frustration I have with TS compared to JS and Python.

bottlepalm3• 3 years ago

What if TypeScript could compile to JS/JSDoc instead of source maps? I'm also not a fan of 'go to definition' bringing me to a dead end d.ts file, but also there has to be a better solution than verbosely JSDoc'ing all the things.

kwhinnery• 3 years ago

Just jumping in here to applaud the usage of "luddite numpties" in a sentence.

FractalHQ• 3 years ago

When I try to google this, the top (and only relevant) result is this hn post… mind throwing a bone?

superjose• 3 years ago

I think this outlines a bigger problem.

JavaScript Ecosystem itself.

It's incredible we do transpiration, minification, bundling to the same language the interpreter is going to read.

markbirbeck• 3 years ago

I've been doing exactly the same thing for a number of years, and I find it a much more intuitive way to use TypeScript.

First, to ensure a focused discussion, I think it's a good idea to separate out TypeScript the transpiler, TypeScript the language, TypeScript the type-checker, and by extension, TypeScript 'types'.

Personally, I don't like transpilers. I never liked CoffeeScript and I hate not being able to see the 'actual' code when looking inside a Docker image in a K8s cluster. I also don't like using non-standard features in a language; I'd far rather live without something that is TS-specific, and if it turns out that this feature has legs, then just wait for it to be included in vanilla JS. (Not to mention that it smacks too much of vendor lock-in, for not much benefit.)

But I do get that this is to some extent because I'm primarily coding to Docker images, rather than multiple browsers. If I want to bump the version of Node to get some new feature, it's pretty easy. So I do recognise that for people working on the client side, where bundling and source maps and all that other chaos is the norm, then transpiliation is no big deal.

(Having said that, back in the day we all used to love that you could hack away on a web app using files on a file system, just loading HTML, JS, and CSS... It's a shame that we seem to have lost the 'vanilla first' approach to software, and leap to preprocessors for everything.)

Anyway... my first point is simply that TypeScript as a _transpiler_ doesn't have any appeal to me.

But I'm not about to throw the baby out with the bath water.

As with the original post, I love types! I think TS types are the best thing to happen in years. Where possible I like to use declaration files as the single source of truth (type first development). From there you can generate GraphQL and OpenAPI schemas, use them to drive contracts for implementation, share the files with other developers using other languages, and so on. And as with this post, I make the connection between the types in the declaration files and the code in the JS files, primarily through inference, and then as necessary through JSDoc.

As with many things, there is going to be a lot of personal preference to this. Since I like the way that Haskell puts type information on a separate line to the function that is being described, it's probably no surprise that I also find the JSDoc approach of putting the types in separately more intuitive.

And since it's easy to configure an editor/IDE to use TSC to lint and provide intellisense on JS files, you can get all of the advantages of TypeScript without having to transpile.

That seems like I pretty good deal to me!

pixel67• 3 years ago

Good on you for making this clear

riogordo2go• 3 years ago

I remember not using/trying Svelte because there was no TS support and it took quite some time before TS support emerged. With that in mind it doesn't surprise me they are not doubling down on TypeScript.

npretto• 3 years ago

this has nothing to do with "TS support" at all.

brundolf2• 3 years ago

*Svelte compiler. Users of Svelte are unaffected

I don't know the details of their situation, but I definitely can relate to the build step being a huge pain in the butt for Node projects. It's why I've stopped using Node whenever I can afford to, in favor of Deno (or maybe one day Bun). I used Deno to build a compiler for a personal language project recently, and it was an absolute delight not having to deal with any of Node's BS. Assuming they can't afford to migrate runtimes at this stage, I definitely get why they'd explore other options

kabes• 3 years ago

I don't care what svelte does, but I've maintained projects with jsdoc types and projects using ts directly and IMO using jsdoc tends to be more of a hassle to maintain, had worse ide guidance and in general felt just more cumbersome.

Being able to click through to the implementation in your ide is nice though, but can be solved by the ide.

cxr2• 3 years ago

Synthesizing the JSDoc-formatted type information into a TypeScript-like syntax for those who prefer it can also be solved by the IDE.

jgalentine007• 3 years ago

As someone who has had a large project go from TypeScript -> TS/JsDoc -> back to TypeScript... I was NOT a fan of trying to use JsDoc for types.

redbar0n• 3 years ago

..and why was that?

bottlepalm3• 3 years ago

Wow so much overhead, but I can see why if the problem is trying to step into some npm package code - landing on a type definition file is not helpful

It makes you think why can't the TS compiler produce JS code with JSDoc annotations instead of source maps. Ship the node packages with that so that debugging into the framework is seamless and easy to edit.

POiNTx• 3 years ago

Little side note, I'm always in awe of the amount of crap open source developers have to take from the community vs the crazy amount of value they offer. There's a lot of backlash on something 99% of commenters will never have to interact with. A lot of knee jerk reactions without trying to understand what's going on. And in return projects like Svelte offer an insane amount of value for people and businesses. Thankless work.

Nowadays it's expected that you get software for free, and if you don't like it you have the moral right to complain at insane lengths at the maintainers of this software. Even if you don't agree with certain decisions (which in this case shouldn't even be the case), there's a way of going about things, you're dealing with people, not faceless corporations.

frankjr• 3 years ago

Wouldn't it be nice if all runtimes and browsers had native support for TS and you could just skip the entire transpiling and source mapping step? Oh, well.

nightski• 3 years ago

Or better yet WASM was a first class citizen and we could abandon JS once and for all.

pjmlp• 3 years ago

Basically this is akin to using C like coding with a C++ compiler, from the looks of it.

ojr• 3 years ago

I still feel vindicated, you don't need Typescript to write type definitions and also type safety on the server/api can be done with Graphql and writing gql

ptrwis• 3 years ago

Regardless of how it ends, it will be a very valuable experience for the entire JS community.

TS to JSDoc Conversion

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