Generate literal type with required and optional properties

[robust oak]

Hi, I'm trying to get this to work:

https://www.typescriptlang.org/play?#code/C4TwDgpgBAGgPAFQHxQLxQN4Cgq6gbQAUoBLAOygGsIQB7AMygQF0AuJo5qCAD2AjIATAM6YoAJwgBHAK4lJg9sHEzoAXygB+KAEMyIKOxlCI9chEEBuLGutZQkJmkw48ACwgAbT7XYYJ0nIKSioQADRQgqY6Mp7A7ACMAEwAzFBqYa64wB6SfgGy8hbs9DqewuGR0bHxUMqq6Zm4alj24NAISc7wyK0AxrRkwsB1EMPsnc7YeFAe3r5QyTZYQA

It should be simple... I'm just missing how to make the keys optional

[spare raft]

@robust oak Here's a shortened URL of your playground link! You can remove the full link from your message.

Orbviox#1805

Playground Link

Preview:```ts
type X<T> = {
[P in keyof T]: T[P] extends {required: true}
? any
: undefined
}

type T = {
hello: {required: true; default: 123}
there: {required: false; default: true}
}

type T2 = X<T>

const test: T2 = {
hello: 12,
}```

You can choose specific lines to embed by selecting them before copying the link.

Gerrit0#7591

Playground Link

Preview:```ts
type Widen<T> = T extends number
? number
: T extends boolean
? boolean
: T extends string
? string
: T

type X<T extends Record<string, {default: unknown}>> =
{
[P in keyof T as T[P] extends {required: true}
? P
: never]: Widen<T[P]["default"]>
} & {
...```

You can choose specific lines to embed by selecting them before copying the link.

[quiet charm]

!ts T2

[spare raft]

type T2 = {
    hello: number;
} & {
    there?: boolean | undefined;
} /* 17:6, 19:13 */```

[quiet charm]

optionality is different from the type including undefined, so if you need both required and optional properties, you need to intersect two mapped types

[robust oak]

thanks a lot! i was trying to find the source code for Vue's prop definitions as well but couldn't navigate - but this helps. thanks again!