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But Svelte obviously doesn't play well with TypeScript, and is kind of its own language - you don't need a source for that. Good luck e.g. getting reactive decl

by johnfn 3y ago

But Svelte obviously doesn't play well with TypeScript, and is kind of its own language - you don't need a source for that. Good luck e.g. getting reactive declarations to play well with TS's type narrowing or null analysis.

nailer 3y ago
I literally hack on TS 5 on Svelte all day and have for a year now (was 4.x originally). Never had a problem with reactive declarations.
losingthefight 3y ago
I couldn't disagree more. Compared to the mess of hooks in React, Svelte is closer to JavaScript in the script portion and closer to normal html in the markup portion. I use vite and TypeScript with each project and never once had a typing issue. Ive built several production apps and consider it far better for my brain than other libraries I tried, and I've been using React since before Redux was mainstream. Svelte is my go to now.
- johnfn 3y ago
  > I couldn't disagree more. Compared to the mess of hooks in React, Svelte is closer to JavaScript in the script portion and closer to normal html in the markup portion. Come now. Only one of React and Svelte needs a custom compiler to run in the browser, and it isn't React...
npn 3y ago
you clearly don't know what you are talking about. reactive declarations do not change the type of the objects. it just that they can rerun when the dependencies change. sure for the convenience of the users you do not need to type `let vars...` for every new variable declared in the reactive statement, but no one forbid you to write it before hand, or let the language server/plugin do it for you. but Svelte indeed do not work perfectly with typescript, because it allows you to write code inside html template, which currently only support javascript expression.
- deleted 3y ago
  [deleted]
- johnfn 3y ago
  This simply isn't true. For instance, if you narrow a variable from `1 | 2 | 3` to `1 | 2`, then trigger a reactive declaration, the reactive declaration can't understand that you've narrowed the variable, and you lose that information. Same thing happens if you go the opposite direction and broaden a variable. TS assumes that program flow roughly goes from top to bottom; if you break that invariant you lose a lot of handy features. > you clearly don't know what you are talking about. huh?
- Volundr 3y ago
  Data-point of one, but I have definitely run into issues where Typescript can't understand what's going on in a reactive expression, and had to aggressively refactor my code to make everything happy. Most of the time it works great, but when it doesn't it can be really annoying. I wouldn't go so far as to say it doesn't play well, but the seams are definitely visible.
  - npn 3y ago
    Could be the plugin was broken somehow. Happen all the time for me. Even now the syntax highlighting and code formatting feature would break if I write the code the wrong way. from my understanding the plugin does some clever tricks like insert some dummy code or create some dummy files to be consumed by the typescript language server. so it is not guaranteed to be correct 100% of the time.
    - MrJohz 3y ago
      I mean, that sounds like a data point of two now to me - you're also saying that Typescript and Svelte don't play that nice together if the plug-in breaks "all the time" and you need to be careful how you write code just to get correct syntax highlighting and code formatting, no?
      - 3y ago
croes 3y ago
https://svelte.dev/blog/svelte-and-typescript https://svelte.dev/blog/svelte-and-typescript

by johnfn 3y ago

nailer 3y ago

I literally hack on TS 5 on Svelte all day and have for a year now (was 4.x originally). Never had a problem with reactive declarations.

losingthefight 3y ago

I couldn't disagree more. Compared to the mess of hooks in React, Svelte is closer to JavaScript in the script portion and closer to normal html in the markup portion. I use vite and TypeScript with each project and never once had a typing issue. Ive built several production apps and consider it far better for my brain than other libraries I tried, and I've been using React since before Redux was mainstream. Svelte is my go to now.

johnfn 3y ago
> I couldn't disagree more. Compared to the mess of hooks in React, Svelte is closer to JavaScript in the script portion and closer to normal html in the markup portion. Come now. Only one of React and Svelte needs a custom compiler to run in the browser, and it isn't React...

npn 3y ago

you clearly don't know what you are talking about. reactive declarations do not change the type of the objects. it just that they can rerun when the dependencies change. sure for the convenience of the users you do not need to type `let vars...` for every new variable declared in the reactive statement, but no one forbid you to write it before hand, or let the language server/plugin do it for you. but Svelte indeed do not work perfectly with typescript, because it allows you to write code inside html template, which currently only support javascript expression.

deleted 3y ago
[deleted]
johnfn 3y ago
This simply isn't true. For instance, if you narrow a variable from `1 | 2 | 3` to `1 | 2`, then trigger a reactive declaration, the reactive declaration can't understand that you've narrowed the variable, and you lose that information. Same thing happens if you go the opposite direction and broaden a variable. TS assumes that program flow roughly goes from top to bottom; if you break that invariant you lose a lot of handy features. > you clearly don't know what you are talking about. huh?
Volundr 3y ago
Data-point of one, but I have definitely run into issues where Typescript can't understand what's going on in a reactive expression, and had to aggressively refactor my code to make everything happy. Most of the time it works great, but when it doesn't it can be really annoying. I wouldn't go so far as to say it doesn't play well, but the seams are definitely visible.
- npn 3y ago
  Could be the plugin was broken somehow. Happen all the time for me. Even now the syntax highlighting and code formatting feature would break if I write the code the wrong way. from my understanding the plugin does some clever tricks like insert some dummy code or create some dummy files to be consumed by the typescript language server. so it is not guaranteed to be correct 100% of the time.
  - MrJohz 3y ago
    I mean, that sounds like a data point of two now to me - you're also saying that Typescript and Svelte don't play that nice together if the plug-in breaks "all the time" and you need to be careful how you write code just to get correct syntax highlighting and code formatting, no?
    - 3y ago

croes 3y ago

https://svelte.dev/blog/svelte-and-typescript https://svelte.dev/blog/svelte-and-typescript