10 JavaScript对象&类&for循环

JavaScript对象

• JavaScript中所有事物都是对象：字符串、数值、数组、函数、数学和正则表达式
• JavaScript允许自定义对象
• JavaScript提供多个内建对象，如String、Date、Array等等。
• 对象是带有属性和方法的特殊数据类型。

创建JavaScript对象：

1 var object = new Object();

<script>
var Person = new Object();
Person.firstName = "腾";
Person.age = "22";
Person.color = "blue";
document.write(Person.firstName + " and age is "+ Person.age + " and color is "+Person.color);
</script>

2 替代语法：

<script>
person = {firstName:"liteng", age:"12"};
document.write(person.firstName + " age " + person.age);
</script>

3 使用对象构造函数,通过new对象的方式来使用

注意：在对象构造方法中添加函数，需要对函数名先进行声明，但不必在对象

<script>
function myFather(firstname,age){
    this.firstname = firstname;
    this.age = age;
    this.changeName = changeName;
    function changeName(name){
        this.firstname = name;
    }
}
myFather = new myFather("liteng","12");
document.write(myFather.firstname + " is " + myFather.age + " years old.");
myFather.changeName("xu");
document.write(myFather.firstname);
</script>

JavaScript类

JavaScript是面向对象的语言，但JavaScript不使用类。即JavaScript中不会创建类，也不会通过类来创建对象。

JavaScript是基于prototype，而不基于类。

<p id="p1">
    点击下面的按钮，循环遍历对象"person"属性
</p>
<button type="button" onclick="myFunction()">点击</button>    
<script type="text/javascript" charset="utf-8">
    function myFunction(){
        var x;
        var txt = "";
        person = {firstName:"liteng" , age:"12"};
        for(x in person){
            txt = txt + person[x];
        }
        document.getElementById("p1").innerHTML = txt;
    }    
</script>