Javascript-简单的计时钟表

 1 <!DOCTYPE html>
 2 
 3 <html lang="en" xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5     <meta charset="utf-8" />
 6     <title>计时钟表</title>
 7     <script type="text/javascript">
 8         function startTime() {
 9             var today = new Date();     //实例化一个日期，创建一个日期对象，内容为当前时间
10             var h = today.getHours();   //获取当前小时存入today
11             var m = today.getMinutes(); //获取当前分钟存入today
12             var s = today.getSeconds(); //获取当前秒存入today
13 
14             m = checkTime(m);    //给分钟不足2位的数十位上加个0
15             s = checkTime(s);    //给秒数不足2位的数十位上加个0
16             document.getElementById("txt").innerHTML = h + ":" + m + ":" + s;   //改变id为txt里的html为 小时：分钟：秒
17             t = setTimeout(function () { startTime() }, 500);                   //在每隔500毫秒后调用startTime()这个方法
18         };
19 
20         //给不足2位的数十位上加个0
21         function checkTime(i) {
22             if (i < 10) {
23                 i = "0" + 1
24             }return i;
25 
26         };
27 
28     </script>
29 </head>
30 <body onload="startTime()">
31     <div id="txt"></div>
32 </body>
33 </html>