javascript 面向对象1

<span style="font-family: Georgia, serif; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; background-color: rgb(245, 245, 213);">Javascript是一种基于对象（object-based）的语言，对象包含</span><span style="font-family: Georgia, serif; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; background-color: rgb(245, 245, 213);">属性"（property）和"方法"（method）</span>

一：声明对象1>原始声明

<span style="color: rgb(17, 17, 17); font-size: 16px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre">	</span>var cat1 = {}; // 创建一个空对象</span>

<pre name="code" class="javascript" style="color: rgb(17, 17, 17); font-size: 16px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px;"><span style="white-space:pre"></span><pre name="code" class="javascript">

<span style="white-space:pre">	</span>cat1.name = "大毛"; // 给对象的属性赋值
<span style="white-space:pre">	</span>cat1.color = "黄色";

2>函数声明

<span style="color: rgb(17, 17, 17); font-size: 16px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; font-family: Arial, Helvetica, sans-serif;"><span>	</span></span><span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 16px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px;">function Cat(name,color){</span><span style="color: rgb(17, 17, 17); font-size: 16px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; font-family: Arial, Helvetica, sans-serif;"><span></span></span><pre name="code" class="javascript">　　　　return {
　　　　　　name:name,
　　　　　　color:color
　　　　}
　　}

<span style="color: rgb(17, 17, 17); font-family: Consolas, Monaco, 'Andale Mono', monospace; font-size: 16px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; background-color: rgb(245, 242, 240);">var cat1 = Cat("大毛","黄色");//实例化一个对象</span>

</pre><pre name="code" class="javascript" style="color: rgb(17, 17, 17); font-size: 16px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px;"><span style="letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; font-family: Georgia, serif; background-color: rgb(245, 245, 213);">3>构造函数</span>

<span style="letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; font-size: 16px; font-family: Arial, Helvetica, sans-serif;">	</span><span style="letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; font-family: Arial, Helvetica, sans-serif; font-size: 16px;">function Cat(name,color){</span>

<pre name="code" class="javascript">　　　　this.name=name;　　　　<pre name="code" class="javascript" style="color: rgb(17, 17, 17); font-size: 19.2000007629395px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px;"><span style="white-space:pre">	</span>this.color=color;

　　}

<span style="font-family: Consolas, Monaco, 'Andale Mono', monospace; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; background-color: rgb(245, 242, 240);"><span style="color: rgb(17, 17, 17); font-family: Consolas, Monaco, 'Andale Mono', monospace; font-size: 16px; letter-spacing: -0.119999997317791px; line-height: 28.7999992370605px; word-spacing: 2.40000009536743px; background-color: rgb(245, 242, 240);">var cat1 = new Cat("大毛","黄色");</span>;//实例化一个对象</span>

实例自动含有一个constructor属性，指向它们的构造函数。alert(cat1.constructor== Cat); //truealert(cat1 instanceof Cat); //true 验证对象类型4〉Prototype模式Javascript规定，每一个构造函数都有一个prototype属性，指向另一个对象。这个对象的所有属性和方法，都会被构造函数的实例继承。这意味着，我们可以把那些不变的属性和方法，直接定义在prototype对象上。　　function Cat(name,color){　　　　this.name = name;　　　　this.color = color;　　}　　Cat.prototype.type = "猫科动物";　　Cat.prototype.eat = function(){alert("吃老鼠")};然后，生成实例。　　var cat1 = new Cat("大毛","黄色");　　var cat2 = new Cat("二毛","黑色");　　alert(cat1.type); // 猫科动物　　cat1.eat(); // 吃老鼠这时所有实例的type属性和eat()方法，其实都是同一个内存地址，指向prototype对象，因此就提高了运行效率。　　alert(cat1.eat == cat2.eat); //true六、 Prototype模式的验证方法为了配合prototype属性，Javascript定义了一些辅助方法，帮助我们使用它。，6.1 isPrototypeOf()这个方法用来判断，某个proptotype对象和某个实例之间的关系。　　alert(Cat.prototype.isPrototypeOf(cat1)); //true　　alert(Cat.prototype.isPrototypeOf(cat2)); //true6.2 hasOwnProperty()每个实例对象都有一个hasOwnProperty()方法，用来判断某一个属性到底是本地属性，还是继承自prototype对象的属性。　　alert(cat1.hasOwnProperty("name")); // true　　alert(cat1.hasOwnProperty("type")); // false6.3 in运算符in运算符可以用来判断，某个实例是否含有某个属性，不管是不是本地属性。　　alert("name" in cat1); // true　　alert("type" in cat1); // truein运算符还可以用来遍历某个对象的所有属性。　　for(var prop in cat1) { alert("cat1["+prop+"]="+cat1[prop]); }