work

archive/proto/user.js

@@ -0,0 +1,16 @@
+```js run
+function User(name, birthday) {
+  let age = calcAge();
+
+  function calcAge() {
+    new Date().getFullYear() - birthday.getFullYear();
+  }
+
+  this.sayHi = function() {
+    alert(name + ', age:' + age);
+  };
+}
+
+let user = new User("John", new Date(2000,0,1));
+user.sayHi(); // John
+```