属性查找原则

function Person(name,age){
      this.name = name;
      this.age = age
    }
    Person.prototype.name = ‘zs‘;
    Object.prototype.gender = ‘male‘;

    var p = new Person(‘mike‘,20)

    console.log(p.name);  //mike
    console.log(p.age);  //20
    console.log(p.gender); //male
    console.log(p.hobby);  //undefined
    console.log(p.toString()); //[object Object]