[Typescript] “keyof”, Generics and Lookup Types

const person = {
    name: "wan",
    age: 28
}

type Person = typeof person 
type PersonKeys = keyof person // "name" | "age"
type PersonKTypes = Person[PersonKeys] // string | number

We can use "keyof" (a unit type) to build a lookup:

function getProperty<T, K extends keyof T>(obj: T ,key: K): T[K] {
    return obj[key]
}

const personName = getProperty(person, 'name')