我們常用的有以下幾種方法來用JavaScript寫一個“類”：

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1. 構造函數(public屬性和方法）

1: function Person(iName, iAge){ 2: this.name=iName; //public 3: this.age=iAge; //public 4: this.ShowStudent=function(){ //public 5: alert(this.name); 6: }; 7: }

以上的屬性和方法都是public的。下面的例子給出private和public的屬性和方法。

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2. 構造函數（public, private屬性和方法）

1: function Person(iName, iAge){ 2: //private field 3: 　var name = iName;　　　　 4: var age = iAge; 5: 　　　　 6: //private method 7: 　var privatefn = function(){　　　　 8: 　　alert(name); 9: 　} 10: 11: return { 12: 　　 //public field 13: Name: "hello " + name, 14: Age: "hello " + age, 15: 16: ShowStudent: function(){ 17: privatefn();　 18: alert(this.Name);　 19: } 20: }; 21: }

調用：(new Person("xiao","10")).ShowStudent();

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3. 原型方法（prototype）

1: function c(){} 2: c.prototype={ 3: name: "init value a", 4: setName: function(iName){ 5: this.name=iName; 6: }, 7: getName: function(){ 8: alert('hello from c, name: ' + this.name); 9: } 10: }; 11: (new c).getName(); // 輸出hello from c, name: init value a

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4. 構造函數+原型方法（prototype）

1: function Person(iName) { 2: this.name = iName; 3: }; 4: ? 5: Person.prototype={ 6: getName: function(){ 7: return this.name; 8: } 9: }; 10: 11: //調用 12: var b = new Person("jack"); 13: alert(b.getName());

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5. 構造函數+原型方法（prototype）- 節省內存的寫法

1: function Person(iName, iAge){ 2: this.name=iName; 3: this.age=iAge; 4: 5: //對象實例都共享同一份方法不造成內存浪費 6: if(typeof Person._initialized == "undefined"){ 7: Person.prototype.ShowStudent=function(){ 8: alert(this.name); 9: }; 10: Person._initialized=true; 11: } 12: } 13: //調用 14: (new Person("jack","20")).ShowStudent();

以上的實現方法如果不用_initialized的方法，也可以指向一個外部函數，道理一樣。

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6. JavaScript類的單例（Singleton）模式寫法

1: var MyNamespace = {}; 2: MyNamespace.Singleton = (function() { 3: var uniqueInstance; // Private attribute that holds the single instance. 4: function constructor() { // All of the normal singleton code goes here. 5: // Private members. 6: var privateAttribute1 = false; 7: var privateAttribute2 = [1, 2, 3]; 8: function privateMethod1() { 9: //... 10: } 11: function privateMethod2(args) { 12: //... 13: } 14: return { // Public members. 15: publicAttribute1: true, 16: publicAttribute2: 10, 17: publicMethod1: function() { 18: // ... 19: }, 20: publicMethod2: function(args) { 21: // ... 22: } 23: } 24: } 25: return { 26: getInstance: function() { 27: if(!uniqueInstance) { // Instantiate only if the instance doesn't exist. 28: uniqueInstance = constructor(); 29: } 30: return uniqueInstance; 31: } 32: } 33: })(); 34: ? 35: //調用: 36: MyNamespace.Singleton.getInstance().publicMethod1();

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JavaScript好書推薦（只推3本，須精讀）

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