如何在Typescript中键入此高级功能？

Question

This is the tricky function :

function getPropertyName(obj, expression) {
    var res = {};
    Object.keys(obj).map(k => { res[k] = () => k; });
    return expression(res)();
}

And my unsuccessful attempt to type it :

  getPropertyName<T>(obj: T, expression: (o: T) => any): string {
    let res = {};
    Object.keys(obj).map(k => { res[k] = () => k; });
    return expression(res as T)();
  }

Answer 1

This will give you no errors, however, your intention is not completely clear to me:

getPropertyName<T>(obj: T, expression: (o: T) => any): string {
    const res: { [key: string]: any } = {};
    Object.keys(obj).map((k) => { res[k] = () => k; });
    return expression(res as T)();
}