Inference for Object.isPrototypeOf()

Hi, I am wondering would be possible to infer types for isPrototypeOf() function same way as it's done with instanceof operator? So we could narrow type of argument if it's been created using Object.create(proto) function and its type would be something like typeof proto if check is fulfilled.

Search Terms

isPrototypeOf

Examples

if (object instanceof HTMLAnchorElement) {
    console.log(object.href);
}

if (HTMLAnchorElement.prototype.isPrototypeOf(object)) {
   console.log(object.href);
}

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• 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.

issue では、実装ファイル、テスト、エントリポイントのいずれも特定されていません。まず instanceof に対する既存の型の絞り込みを見つけ、次に Object.isPrototypeOf() の例で Object.create(proto) によって作成されたオブジェクトをどのように絞り込むべきかを評価してください。提案された動作が仕様化され、適切な compiler tests でカバーされていれば完了です。