//动态原型模式
        function Person(name, age, job) {
            this.name = name;
            this.age = age;
            this.job = job;
            if(typeof this.sayName!="function") {
                this.sayName = function () {
                    alert(this.name);
                };   
            }
            if(typeof this.sayInfo!="function") {
                this.sayInfo = function() {
                    console.log(this.job);
                };
            }
        }
//javascript/6976