8. 对象超类

ES6 允许在对象中使用 super 方法：

var parent = {
  foo() {
    console.log("Hello from the Parent");
  }
}
var child = {
  foo() {
    super.foo();
    console.log("Hello from the Child");
  }
}
Object.setPrototypeOf(child, parent);
child.foo(); // Hello from the Parent
             // Hello from the Child