Advanced TypeScript series. Would you be interested?

#discuss #typescript #javascript

Planning to run some advanced TS series on dev.to. Plan is to go through some really sofisticated examples of type system usage. Whould you be interested in such? And If so, what topic would be most interesting for you?

Top comments (16)

Pacharapol Withayasakpunt • Jan 24 '20 • Edited

Writing @types folder, rather than simply declare module 'xxx'
How to contribute to a JavaScript project by writing index.d.ts
How to decide on configuring tsconfig.json, and why?

Adam Crockett 🌀 • Jan 24 '20 • Edited

Honestly you don't have to write a .d.ts these days, tsconfig can let you generate one with one of its many options (to drunk to look it up sorry)

Edit: for js authored libs you can use Microsoft's cli tool as seen bellow.

Pacharapol Withayasakpunt • Jan 25 '20 • Edited

This is actually not true. There are too many pure JavaScript projects with or without JSDoc (and sometimes TypeScript IntelliSense just doesn't read JSDoc...) That's why github.com/DefinitelyTyped/Definit... exists, which are actually hand-written *.d.ts's.

(Though, I know it is possible to generate *.d.ts from JSDoc. I do that sometimes.)

You can also add *.d.ts to a pure JavaScript project of someone else, without submitting to DefinitelyTyped. Even if they don't merge the PR, npm install *.git from GitHub is definitely an option.

Adam Crockett 🌀 • Jan 25 '20

Ah ... Of course, I wasn't thinking about this context where a library was not originally authored in Typescript (but I was drunk so you can let me off). I'm sure there is tooling to introspect JavaScript libs and generate .d.ts files anyway. When there's a will there's a way.

Pragmatic Maciej • Jan 25 '20

Yes there is github.com/microsoft/dts-gen

Adam Crockett 🌀 • Jan 25 '20

Thank you Maciej and thank you Microsoft.

So you see a definition file is not desirable to hand write because, it's bad enough maintaing code that actually do something, can you imagine refactoring this every time you make a change as well, people would rage quit typescript. I used to do it by hand then decide I cba. But there we go, you can and should generate as much as possible.

Adam Crockett 🌀 • Jan 24 '20

tsconfig is like glasses, stick to the default you will know what to change / lookup when things are not working the way you want.

e1cb4 ac37s • Jan 24 '20

There is package 'foo' which has '@types/foo' and the latter is used in project. The latter has some types/interfaces declared wrong (not fully typed or actually wrong). How to extend or rewrite those fishy places in local types not abandoning all other parts of original "@types..."?

Dan Silcox • Jan 24 '20

Not sure how ‘experimental’ the ‘experimental decorators’ still are, thought about trying to implement a custom one the other day but kind of gave up! Maybe you could go into a bit more detail on how they work, when to/not to use them, etc?