function IElectricalEquipment() {

        }

        IElectricalEquipment.prototype = {

            poweron: function () {

            },

            poweroff: function () {

            }

        };

        function Fan(){//电风扇

        }

        Fan.prototype=new IElectricalEquipment;

        Fan.prototype.poweron=function(){

            console.log("Fan'power on")

        };

        Fan.prototype.poweroff=function(){

            console.log("Fan'power off")

        };

        function Light(){//电灯

        }

        Light.prototype=new IElectricalEquipment;

        Light.prototype.poweron=function(){

            console.log("Light'power on")

        };

        Light.prototype.poweroff=function(){

            console.log("Light'power off")

        };

        var createSwitch=(function () {

            function Switch(){

                this.equipment=null;

            }

            Switch.prototype={

                on:function(){

                    this.equipment.poweron();

                },

                off:function(){

                    this.equipment.poweroff();

                }

            };

            return function(){

                return new Switch();

            }

        }());

        var myLight=new Light();

        var myFan=new Fan();

        var FanSwitch=createSwitch();

        FanSwitch.equipment=myFan;

        FanSwitch.on();

        FanSwitch.off();

        FanSwitch.equipment=myLight;

        FanSwitch.on();

        FanSwitch.off();