JavaScript接口的實現三種方式(推薦)

Javascript模仿接口可以有三種方式：1.註釋法2.檢查屬性法3.鴨式辨形法

1.註釋法:此方法屬於程序文檔範疇，對接口的繼承實現完全依靠程序員自覺

/*interface People{function createHead();function createBody();}*/var woman = function(name){ //implements People interfacethis.name = name;}woman.prototype.showName = function(){alert(this.name);}woman.prototype.createBody = function(){ //實現必要的方法alert("身體已經創建好");}woman.prototype.createHead = function(){alert("頭部已經創建好");}

//2.屬性檢查法：把要實現的接口方法添加到類屬性列表裡，通過定義好的檢測反複檢查是否已經實現了那些方法

//優缺點：可以強迫程序員實現接口，沒實現就報錯。不過雖然聲明了自己實現了哪些方法，但實現時很可能有遺漏

/*interface People{function createHead();function createBody();}*/var woman = function(name){this.name = name;this.implementsInterfaces = ['People'];}woman.prototype.showName = function(){alert(this.name);}woman.prototype.createBody = function(){ //實現必要的方法alert("身體已經創建好");}woman.prototype.createHead = function(){alert("頭部已經創建好");}function implement(obj,interfaces){for(var i=1;i<interfaces.length;i++){var interfaceName = interfaces[i];var interfaceFound = false;for(var j=0;j<obj.implementsInterfaces.length;j++){if(obj.implementsInterfaces[j] = interfaceName){interfaceFound = true;break;}}if(!interfaceFound){return false;}}return true;}function isImplememts(instance,interfaces){ //判斷對像是否已經繼承相應接口if(!implement(instance,interfaces)){throw new Error("Object doesn't implement a required interface");}}

3.鴨式辨型法：（不通過外表判斷鴨子，而通過其是否有鴨子的特性來判斷。如James Whitcomb Riley所說，像鴨子一樣走路並且嘎嘎叫的就是鴨子）

上面倆種都聲明了自己實現了那些接口，其實聲明不重要，實現接口核心的是類實現了接口方法集。如果類具有了接口定義的所有方法函數名相同的函數，那麼認為它實現了接口

//接口類，用來創建接口var Interface = function(name,motheds){if(agruments.length!=2){throw new Error("Interface constructor called with "+arguments.length+"arguments,but expected exactly 2");}this.name = name;this.methods = [];for(var i=0;i<motheds.length;i++){if(typeof motheds[i] !== 'string'){throw new Error('Interface constructor expects mothed names to be'+'passes in as a string');}this.methods.push(motheds[i]);}}Interface.prototype.ensureImplements = function(objs){if(agruments.length != 1){throw new Error("Interface constructor called with "+arguments.length+"arguments,but expected exactly 1")}for(var i=0;i<objs.length;i++){var obj = objs[i];for(var j=0;j<this.motheds.length;j++){var mothed = this.methods[j];if(!obj[mothed] || !typeof obj[mothed] !== 'function'){throw new Error('Function Interface.ensureImplements:implements interface'+this.name+',obj.mothed'+mothed+'was not found');}}}}//創建接口var People = new Interface('People',['createHead','createBody']);//子類var Woman = function(name){this.name = name;this.implementsInterfaces = ['People'];}Woman.prototype.showName = function(){alert(this.name);}Woman.prototype.createBody = function(){ //實現必要的方法alert("女人身體已經創建好");}Woman.prototype.createHead = function(){alert("女人頭部已經創建好");}//子類var Man = function(name){this.name = name;this.implementsInterfaces = ['People'];}Man.prototype.showName = function(){alert(this.name);}Man.prototype.createBody = function(){ //實現必要的方法alert("男人身體已經創建好");}Man.prototype.createHead = function(){alert("男人頭部已經創建好");}//判斷是否實現Poeple.ensureImplements(['Woman','Man']);