TypeScript definitions for my packages

[sindresorhus]

@BendingBender is helping me adding TypeScript definitions to a lot of my packages: https://github.com/search?q=user%3Asindresorhus+author%3ABendingBender+is%3Apr+typescript 🙌

We can use this space to discuss high-level things.

[sindresorhus]

@BendingBender Would you be able to prioritize https://github.com/sindresorhus/electron-better-ipc ? I've gotten a couple of emails about doing TypeScript definitions for it.

[BendingBender]

Will do next.

[BendingBender]

Note to myself: clarify usage of Array/ReadonlyArray in https://github.com/sindresorhus/typescript-definition-style-guide

[sindresorhus]

@BendingBender When a function returns an array, should we make it readonly?

foo(bar: string): readonly string[];

Or is it pointless?

[BendingBender]

I wouldn't do it. I would usually expect a library to give me something I can use for every purpose, not something unnecessary limited. Otherwise I would have to cast/copy the array, this is not very nice ergonomics-wise.

[sindresorhus]

@BendingBender That's a very good point. So readonly for all input, but never readonly for return values. Correct? If so, I'll update the style guide.

[sindresorhus]

@BendingBender Would you be able to prioritize https://github.com/sindresorhus/linkify-urls and https://github.com/sindresorhus/linkify-issues? We need it for Refined GitHub.

Context: https://github.com/sindresorhus/refined-github/pull/1783/files#diff-98a7886093e2e560968c34d6c4707b22R11

[sindresorhus]

@BendingBender Node.js 12 is out, so would be great if you could add it to .travis.yml when you do PRs. Like: sindresorhus/got@bf1aa54#diff-354f30a63fb0907d4ad57269548329e3R3

[BendingBender]

Will do.

[sindresorhus]

@BendingBender I know you didn't do this type definition, but would you be able to help convert it to CommonJS-style? https://github.com/chalk/chalk/blob/master/index.d.ts (It can be a breaking change as we're planning a major release there)

[fregante]

Like sindresorhus/memoize#32 ?

[sindresorhus]

@bfred-it Yup

[BendingBender]

I know you didn't do this type definition, but would you be able to help convert it to CommonJS-style? chalk/chalk:index.d.ts@master (It can be a breaking change as we're planning a major release there)

Done.

[sindresorhus]

@BendingBender Is there any way to get VS Code and other editors to show the resolved properties? I have this https://github.com/sindresorhus/crypto-random-string/blob/32365366245e602a58a2a38c4d6fc2edd30355d7/index.d.ts#L52 and it shows up as something completely unreadable:

Alternatively, a better way to write the definition.

[BendingBender]

As far as I can see it, there is no better way to type this without giving up the exclusivity of type/characters options.

I think that this definition would be clearer:

interface BaseOptions {...}
interface TypeOptions extends BaseOptions {...}
interface CharactersOptions extends BaseOptions {...}

type Options = MergeExclusive<TypeOptions, CharactersOptions>;

But it is still rendered quite ugly in the suggestion tooltip.

The only other way I can think of is to use discriminated union types, but I have no idea how to do this here without hurting ergonomics:

interface BaseOptions {...}
interface TypeOptions extends BaseOptions {
	kind: 'types';
	type?: 'hex' | 'base64' | 'url-safe';
}
interface CharactersOptions extends BaseOptions {
	kind: 'characters';
	characters?: string;
}

type Options = TypeOptions | CharactersOptions; // <- this one always needs the 'kind' property :-(

[ExE-Boss]

You could do:

interface BaseOptions { … }
interface TypeOptions extends BaseOptions {
	kind: 'types';
	type?: 'hex' | 'base64' | 'url-safe';
}
interface CharactersOptions extends BaseOptions {
	kind: 'characters';
	characters?: string;
}

// No longer needs the `kind` property:
type Options = BaseOptions | TypeOptions | CharactersOptions;

[BendingBender]

@ExE-Boss Sorry but I've tried this before, this basically renders the type a non-discriminated union type. Thus all properties simply become optional and non-exclusive.

[sindresorhus]

Hmm, too bad. Really wish TypeScript and VS Code had a better way to handle this.

[sindresorhus]

@BendingBender Would you be able to prioritize https://github.com/sindresorhus/mimic-response ?

[ExE-Boss]

I’m in the process of writing the type definitions for mimic-response.