对象

function Person(first, last, age, eyecolor) {
    this.firstName = first;
    this.lastName = last;
    this.age = age;
    this.eyeColor = eyecolor;
}
var myFather = new Person("Bill", "Gates", 62, "blue");
var myMother = new Person("Steve", "Jobs", 56, "green");

有时，希望向所有给定类型的已有对象添加新属性（或方法）。有时，希望向对象构造器添加新属性（或方法）。

JavaScript prototype 属性允许您为对象构造器添加新属性：

function Person(first, last, age, eyecolor) {
    this.firstName = first;
    this.lastName = last;
    this.age = age;
    this.eyeColor = eyecolor;
}
Person.prototype.nationality = "English";
Person.prototype.name = function() {
    return this.firstName + " " + this.lastName;
};