面向对象（继承）--借用构造函数02

首先回想一下原型链中援用类型值带来的问题

function SuperType() {
    this.colors = ["red", "blue", "green"];
}
 
function SubType() {}
//继承了 SuperType
SubType.prototype = new SuperType();
var instance1 = new SubType();
instance1.colors.push("black");
alert(instance1.colors); //"red,blue,green,black"
var instance2 = new SubType();
alert(instance2.colors); //"red,blue,green,black"
function SuperType() {