lookup types

keyof.ts

function spyOn<O extends object, P extends keyof O>(obj: O, prop: P) {
    console.log(obj, prop);
}

interface IPerson {
    name: string,
    age: number
}

const person: IPerson = {
    name: 'John',
    age: 54
};

type keys = keyof IPerson; 

spyOn(person, 'address'); // Catch error