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How do you feel about TypeScript? (lemmygrad.ml)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/programming

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Specifically, do you worry that Microsoft is going to eventually do the Microsoft thing and horribly fuck it up for everyone? I've really grown to appreciate the language itself, but I'm wary of it getting too ingrained at work only to have the rug pulled out from under us when it's become hard to back out.

Edit: not really "pulling the rug", but, you know, doing the Microsoft classic.

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[–] Kalabasa 6 points 1 year ago (2 children)

What are the additional requirements? Afaik valid JS is valid TS.

[–] [email protected] 2 points 1 year ago* (last edited 1 year ago) (2 children)

var foo = {};
foo.bar = 42;

Perfectly valid, and extremely commonly used, coding pattern in JavaScript - it's essentially the normal way to do an associative array or hashmap in JavaScript. It's also one of the commonly used ways to (poorly) simulate OOP in JavaScript.

In TypeScript, it fails. You can't treat an object as an arbitrary key/value pair. That's a good thing... but still, it means TypeScript is not a superset of JavaScript.

AFAIK that source code will be accepted by the TypeScript compiler if the file has a *.js extension, but that's an ugly workaround and it also means you can't copy/paste code between files. You have to rewrite the code.

[–] [email protected] 8 points 1 year ago (2 children)

In TypeScript, it fails. You can't treat an object as an arbitrary key/value pair. That's a good thing... but still, it means TypeScript is not a superset of JavaScript.

No, it doesn't fail. It compiles to perfectly valid JS that runs exactly as you'd expect. The type checking itself errors, because you've made an error - but the compilation isn't prevented by this error.

So yes, Typescript is a superset of JavaScript.

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (1 children)

That is an important difference. Still lots of people, myself included, classify "compiler printing an error (not a warning)" as failure, even if bizzarly the code still runs somehow.

[–] [email protected] 1 points 1 year ago

That's because you're missing the distinction between compiler and type checker. The compiler doesn't check types, it strips them. The type checker only checks types, it doesn't compile. They are often used in conjunction, though increasingly the compilation is done by e.g. esbuild.

But there is nothing "bizarre" about the code running, since literally, TS is a superset of JS.

[–] [email protected] 1 points 1 year ago (1 children)

Wouldn't it fail in strict mode?

[–] [email protected] 1 points 1 year ago

The type checking does, but not the compilation.

[–] [email protected] 2 points 1 year ago (1 children)

Doesn't change the fact that you can strip types and get js

[–] lolcabanon 1 points 1 year ago

I know a cool library you can use to convert .ts files in Js! It's called tsc!

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago)

Type annotations. It can be as simple a adding any in front of parameters, but there are other edgecases too, and when you have a really big codebase it can be a pain to convert.