keyof example
12345678910111213
function getProperty<T, K extends keyof T>(obj: T, key: K) {
return obj[key]; // Inferred type is T[K]
}
function setProperty<T, K extends keyof T>(obj: T, key: K, value: T[K]) {
obj[key] = value;
}
let x = { foo: 10, bar: "hello!" };
let foo = getProperty(x, "foo"); // 10
console.log(foo);
TypeScript
INFO