var Interface = function(name, methods) {
 if(arguments.length != 2) {
 throw new Error("Interface constructor expected exactly 2.");
 }
 this.name = name;//接⼝名称
 this.methods = [];//接⼝的⽅法名称数组
 for(var i = 0, len = methods.length; i < len; i++) {
 if(typeof methods[i] !== 'string') {
 throw new Error("Interface constructor expects method names is 
String.");
 }
 this.methods.push(methods[i]);
 }
};
Interface.ensureImplements = function(object) {
 if(arguments.length < 2) {
 throw new Error("Interface.ensureImplements exactly arguments at least 
2.");
 }
 for(var i = 1, len = arguments.length; i < len; i++) {
 var interface = arguments[i];
 if(interface.constructor !== Interface) {
 throw new Error(interface + "exactly type is Interface.");
 }
 for(var j = 0, methodsLen = interface.methods.length; j < methodsLen; 
j++) {
 var method = interface.methods[j];
 if(!object[method] || typeof object[method] !== 'function') {
 throw new Error("Function Interface.ensureImplements: object "
 + "does not implement the " + interface.name
 + " interface. Method " + method + " was not found.");
 }
 }
 }
};

//模拟使⽤
//定义了接⼝Person0和Person1,并在每个接⼝中定义三个⽅法
var Interface0 = new Interface('Person0', ['add', 'del', 'getItem']);
var Interface1 = new Interface('Person1', ['add', 'del', 'getItem']);
function addForm(myClassInstance){
 //⽤来检查myClassInstance是否实现了接⼝Interface0和Interface1
 Interface.ensureImplements(myClassInstance, Interface0, Interface1)
}