-
-
Save aztack/3ef6d80bcfaea8f12f6e2cb89f68b9c5 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// jonschlinkert/is-object | |
type IsObjectObject<T> = T extends | |
| AnyArray | |
| AnyFunction | |
| boolean | |
| null | |
| number | |
| string | |
| symbol | |
| undefined | |
? false | |
: true; | |
// jonschlinkert/is-plain-object | |
type HasNoModifiedConstructor< | |
T extends Object | |
> = T["constructor"] extends AnyFunction ? true : false; | |
type HasNoModifiedPrototype<T extends Object> = IsObjectObject< | |
T["constructor"]["prototype"] | |
> extends true | |
? true | |
: false; | |
// T extends {isPrototypeOf: any} as a T.hasOwnProperty('isPrototypeOf') | |
type PrototypeHasObjectSpecificMethod< | |
T extends Object | |
> = T["constructor"]["prototype"] extends { isPrototypeOf: any } ? true : false; | |
// IsObjectObject<T> && HasNoModifiedConstructor<T> && HasNoModifiedPrototype<T> && PrototypeHasObjectSpecific<T> | |
type IsPlainObject<T> = IsObjectObject<T> extends true | |
? (HasNoModifiedConstructor<T> extends true | |
? (HasNoModifiedPrototype<T> extends true | |
? (PrototypeHasObjectSpecificMethod<T> extends true ? true : false) | |
: false) | |
: false) | |
: false; | |
// no :( | |
type IsPlainActuallyPlain = IsPlainObject<{}>; // $ExpectType true | |
type ObjectIsPlain = IsPlainObject<object> // $ExpectType true | |
const obj = {} | |
// no :( | |
type IsValueObjectPlain = IsPlainObject<typeof a>; // $ExpectType true | |
declare function isPlainObject(obj: any): boolean; | |
function takePlainObject<T>(obj: T): IsObjectObject<T> extends true ? number : never { | |
if (!isPlainObject(obj)) { | |
throw new Error('gib me plain'); | |
} | |
// @ts-ignore | |
return 1; | |
} | |
type ForcePlain<T> = IsObjectObject<T> extends true ? T : never; | |
function takeForcedPlainObject<T>(obj: ForcePlain<T>): number { | |
if (!isPlainObject(obj)) { | |
throw new Error('gib me plain'); | |
} | |
return 1; | |
} | |
const good = takePlainObject({}); | |
// no compile error but at least never | |
const bad = takePlainObject([]); | |
// typescript infers T to be {} | |
const badForced = takeForcedPlainObject([]); | |
// $ExpectError | |
const hintedBadForced = takeForcedPlainObject<any[]>([]); | |
const anArray: number[] = []; | |
// again ts infers T to be {} | |
const typedBadForced = takeForcedPlainObject(anArray); |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment