var Classroom=function() { this.numberOfPeople=0; this.onFull=null; this.peopleEnter=function(number) { this.numberOfPeople+=number; if(this.numberOfPeople>60&&this.onFull!=null) { this.onFull(this.numberOfPeople); } } } function show1(number) { alert("教室里有"+number+"人"); } function show2(number) { alert("教室里超出了"+(number-60)+"人"); } var classroom1=new Classroom(); classroom1.onFull=show1; classroom1.peopleEnter(30); classroom1.peopleEnter(32); classroom1.onFull=show2; classroom1.peopleEnter(34);