How come this works in the playground but not in my ide?

[slow sage]

U9G#0670

Playground Link

Preview:```ts
type ObjectKeys<T> = T extends object
? (keyof T)[]
: T extends number
? []
: T extends Array<any> | string
? string[]
: never

interface ObjectConstructor {
keys_<T>(o: T): ObjectKeys<T>
}

Object.keys_({a: 1})```

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

[scarlet stone]

I have this in my tsconfig: ```json
{
"compilerOptions": {
"lib": ["ESNext"],
"module": "esnext",
"target": "esnext",
"moduleResolution": "nodenext",
"strict": true,
"downlevelIteration": true,
"skipLibCheck": true,
"jsx": "preserve",
"allowSyntheticDefaultImports": true,
"forceConsistentCasingInFileNames": true,
"allowJs": true,
"types": [
"bun-types" // add Bun global
],
"resolveJsonModule": true
}
}

However

but only when it's in the middle of a file

when it's in it's own file it works fine

here, it doesnt work for some reason?

[slow sage]

U9G#0670

Playground Link

Preview:```ts
type ObjectKeys<T> = T extends object
? (keyof T)[]
: T extends number
? []
: T extends Array<any> | string
? string[]
: never

interface ObjectConstructor {
keys_<T>(o: T): ObjectKeys<T>
}

Object.keys_({a: 1})

export type Split<
S extends string,
D
...```

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

[viscid furnace]

@scarlet stone Files without import or export are global modifying scripts.

[scarlet stone]

how do I share the changes the to my whole project?

[scarlet stone]

Okay, I see

so deleting my tsconfig.json allows this to compile

type ObjectKeys<T> = T extends object
    ? (keyof T)[]
    : T extends number
    ? []
    : T extends Array<any> | string
    ? string[]
    : never

interface ObjectConstructor {
    keys_<T>(o: T): ObjectKeys<T>
}

const b = Object.keys_({ a: 1 })

but with this tsconfig, it didn't compile

{
    "compilerOptions": {
        "lib": ["ESNext"],
        "module": "esnext",
        "target": "esnext",
        "moduleResolution": "nodenext",
        "strict": true,
        "downlevelIteration": true,
        "skipLibCheck": true,
        "jsx": "preserve",
        "allowSyntheticDefaultImports": true,
        "forceConsistentCasingInFileNames": true,
        "allowJs": true,
        "types": [
            "bun-types" // add Bun global
        ],
        "resolveJsonModule": true
    }
}

[viscid furnace]

@scarlet stone You can put the code in a non-module file - or use a declare global block. I don't really think this behavior is particularly tsc-related.

FWIW, modifying Object.prototype is generally considered not a great idea - maybe you should just put this in a utility function and import it?

[scarlet stone]

Im not modifying it, I’m just giving Ovject.keys a better type, i was just testing with the _ since it’s easier to see if the changes applied

[viscid furnace]

@scarlet stone FWIW, that's not actually a 'better' type - the built-in type is the correct, safe type. (Though the unsafe type is useful, too)

!*:unsafe-keys

[slow sage]

Retsam19#2505

`!retsam19:unsafe-keys`:

Since TS allows objects to have extra properties not specified in the type, it doesn't assume that all the keys on the type are the only keys on the object. This means that Object.keys returns string[] not a specific type, and for(const key in obj), key is string, (not keyof typeof obj).

If you wish to assume otherwise, this utility is often helpful:

// A signature for `Object.keys` that assumes the only keys are the ones indicated by the type
const unsafeKeys = Object.keys as <T>(obj: T) => Array<keyof T>;

[scarlet stone]

Yeah, that makes sense, but it would be a lot easier if i could just as const the object and it would get that type for free

Otherwise I have to scavenge for these types