title: Typescript interface variable clone
body: <p>I know the <code>interface</code> of the typescript is a Type, so if I define an interface, I can use it to define a variable. My question is that, is there any (pre-defined) method to copy a variable of an interface? for example: </p>
  
  <pre><code>interface Person {
    name: string;
    birthday: string;
  }
  let person: Person = &lt;Person&gt;{};
  person.name = "bob";
  person.birthday = "19000909";
  console.dir(person);
  let copyPerson: Person = &lt;Person&gt;{};
  copyPerson = person;
  copyPerson.name = "Alice";
  //then the person's name is also Alice. because the reference of person is passed to copyPerson.
  </code></pre>
  
  <p>after I change the <code>copyPerson</code>, the <code>person</code> will change too. I know I can just assign the every property of the <code>person</code> to the <code>copyPerson</code>, but is there any method to make a separate copy of person? (By the way, if it is class, I can <code>new</code> an object)</p>