《学习typescript》一 接口

interface Person {
  firstName: string;
  lastName: string;
}

function greeter(person: Person) {
  return "Hello, " + person.firstName + " " + person.lastName;
}

// let user = "Jane User";
let user = {firstName: "Jane", lastName: 'bbbb'};
document.body.innerHTML = greeter(user);

通过interface定义接口，person: Person 继承接口。