获取HTML对象

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>

    </head>
    <body>
        <!--DOM Document Object Model-->

        <div id="one">
            <span class="one">DOM Document Object Model</span>
            <p>Hello World</p>
        </div>
        <div id="two" >
            <span >DOM Document Object Model</span>
            <p>Hello World</p>
        </div>
        <div id="three">
            <span name = "last">DOM Document Object Model</span>
            <p>Hello World</p>
        </div>
    </body>
</html>

1.通过id获取document对象
　 var div = document.getElementById("one");
2.通过tagName与标签名获取document对象可以直接由任意对象调用
　 var div = document.getElementsByTagName("div");
3.通过classname与类名可以直接由任意对象调用
　 var arr1 = document.getElementsByClassName("one");
4.通过标签的name值来查找
　 var arr1 = document.getElementsByName("last");