DOM方法(getElementById, getElementsByTagName, getAttribute, setAttribute)

getElementById() 方法

document.getElementById(id) 返回一个对象

alert(typeof document.getElementById("content"));

getElementsByTagName() 方法

element.getElementsByTagName(tag) 返回一个对象数组

alert(document.getElementsByTagName("div").length);

var element = document.getElementById("content");
var oElement = element.getElementsByTagName("li");
alert(oElement.length);

getAttribute() 方法

object.getAttribute(attribute) 返回元素节点的属性值

var oElement = document.getElementsByTagName("div");
for(var i = 0; i < oElement.length; i++){
alert(oElement[i].getAttribute("title"));
}

setAttribute() 方法

object.setAttribute(attribute, value) 对元素节点属性值做出修改

var element = document.getElementById("content");
element.setAttribute("title", "a list of goods");

Examples:

1 <ul id="list">
2 <li>one</li>
3 <li>two</li>
4 </ul>
5 <script type="text/javascript">
6 <!--
7 var element = document.getElementById("list");
8 var oElement = element.getElementsByTagName("li");
9 alert(typeof element);
for(var i = 0; i < oElement.length; i++){
alert(typeof oElement[i]);
}

element.setAttribute("title", "Hello world!");
alert(element.getAttribute("title"));
-->
</script>