练习：----点击按钮文字变颜色

点击按钮文字变颜色
 1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 2 <html xmlns="http://www.w3.org/1999/xhtml">
 3 <head>
 4 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 5 <title></title>
 6 </head>
 7 
 8 <body>
 9 <p id="hello">hello</p>
10 <input type="button"  style="cursor:pointer;"   value="点击变颜色"  onclick="hello()" />
11 <br/>
12 </body>
13 
14 <script language="javascript">
15 var a= new Array();
16 a[0]=2;
17 a[1]=1;
18 a[2]=3;
19 a.sort();/*从小到大排序*/
20 a.reverse();/*数组翻转*/
21 document.write(a);/*输出321*/
22 
23 var a=true;
24 function hello()
25 {
26 if(a)
27 {     
28      x=document.getElementById("hello");
29      x.style.color = "#ff0000";
30      a=false;
31 }
32 else
33     {    
34     y=document.getElementById("hello");
35     y.style.color="#000000";
36     a=true;
37     }
38 }
39 </script>
显示效果：