原型

function Student(name, age) {
this.name = name;
this.age = age;
}

    Student.prototype.study = function(){
        console.log(this.name + " 开始学习...");
    };

    var stu = new Student("张三", 18);
    console.log(stu.name);
    console.log(stu.sex); // undefined
    stu.study();

    // hasOwnProperty()
    console.log(stu.hasOwnProperty("eat")); // false
    console.log(stu.hasOwnProperty("name")); // true
    console.log(stu.hasOwnProperty("toString")); // true
    console.log(stu.hasOwnProperty("study")); // true
    // in
    console.log("name" in stu); // true
    console.log("study" in stu); // true
    console.log("toString" in stu); // true

    // isPrototypeOf()
    console.log(Student.prototype.isPrototypeOf(stu)); // true
    console.log(Array.prototype.isPrototypeOf(stu)); // false
    console.log(Object.prototype.isPrototypeOf(stu)); // true

    // Object.create()
    var stu3 = Object.create(Student.prototype); // stu3.__proto__ = Student.prototype
    console.log(stu3);
    stu3.study();

    stu.eat(); // undefined(); 报错

    var stu2 = new Student("李四", 19);
    stu2.study();

    console.log(stu.study == stu2.study)

    console.log(stu.toString);