Add typed overloads to `Object.create`

Search Terms

• object.create
• object create
• typed object.create
• typed object create

Suggestion

Change the signatures of Object.create to:

interface ObjectConstructor {
	create<P extends object | null>(proto: P): null extends P ? {} : P;

	create<
		P extends object | null,
		M extends PropertyDescriptorMap = {}
	>(proto: P, properties?: M & ThisType<any>): {
		readonly [
			K in keyof M as M[K] extends { readonly writable: false }
				? K
				: never
		]: M[K] extends Readonly<TypedPropertyDescriptor<infer V>>
			? V
			: any;
	} & {
		-readonly [
			K in keyof M as M[K] extends { readonly writable: true }
				? K
				: never
		]: M[K] extends Readonly<TypedPropertyDescriptor<infer V>>
			? V
			: any;
	} & (null extends P ? {} : P);
}

Use Cases

Getting correct types in code that does:

// `foo` is `any`, because `T` of Object.assign<T, U> is `any`:
const foo = Object.assign(
	// `T` is currently typed as `any`:
	Object.create(null),

	// Only `U` is typed correctly as { bar: number; baz: string }:
	{
		bar: 123,
		baz: 'biz',
	},
);

Examples

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
  • This might need a flag similar to strictBindCallApply, or just done in a separate lib file.
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

Relevant issues

• https://github.com/microsoft/TypeScript/issues/1108
• https://github.com/microsoft/TypeScript/issues/13206
• https://github.com/microsoft/TypeScript/issues/18609
• https://github.com/microsoft/TypeScript/issues/38385
• https://github.com/microsoft/TypeScript/issues/41424

提案されている ObjectConstructor.create のオーバーロードと、リンクされている issue #1108、#13206、#18609、#38385、#41424 から始めてください。現在のライブラリ宣言と互換性に関する懸念をどのように扱うべきかを判断してください。Object.create が JavaScript のランタイム動作を変更せずに要求された型情報を提供できれば完了です。