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有些类型可以是字面量而非对象:如字符串、数值、布尔值
- 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>