javascript 数字时钟

初学js,所以安装案例做了个非常简单的数字时钟,显示系统当前的时间
  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>js数字时钟</title>
  6 </head>
  7 
  8 <body onload="showTime()">
  9 <p id="time">显示时间的</p>
 10 <div>
 11   <input type="button" onclick="showDate()"  value="显示时间"/>
 12   <p id="date">显示日期</p>
 13 </div>
 14 <script type="text/javascript" language="javascript">
 15 
 16 var months = ["一月","二月","三月","四月","五月","六月","七月","八月","九月","十月","十一月","十二月"];
 17 var weekdays = new Array("星期日","星期一","星期二","星期三","星期四","星期五","星期六");
 18 var currentTime;
 19 
 20 function showDate()
 21 {
 22     var date = new Date();
 23     
 24     var year = date.getFullYear(); //getYear();
 25     var month = undefined;
 26     var day = date.getDate();
 27     var weekday = undefined;
 28     for(var i=0 ;i<months.length ;i++)
 29     {
 30         if(date.getMonth()==i)
 31         {
 32             month = i+1 ; //months[i];
 33         }    
 34     }
 35     
 36     switch(date.getDay())
 37     {
 38         case 0:
 39             weekday = weekdays[0];
 40             break;
 41         case 1:
 42             weekday = weekdays[2];
 43             break;
 44         case 2:
 45             weekday = weekdays[2];
 46             break;
 47         case 3:
 48             weekday = weekdays[3];
 49             break;
 50         case 4:
 51             weekday = weekdays[4];
 52             break;
 53         case 5:
 54             weekday = weekdays[5];
 55             break;
 56         case 6:
 57             weekday = weekdays[6];
 58             break;
 59             
 60     }
 61 
 62     document.getElementById("date").innerHTML = "现在时间是:<br>" + year + "年" + month + "月" + day + "日  " + weekday + " " + currentTime;
 63 }
 64 
 65 //显示时间
 66 function showTime()
 67 {
 68     var date = new Date();
 69     var hour = date.getHours();
 70     var mins = date.getMinutes();
 71     var sec = date.getSeconds();
 72     
 73     hour = checkTime(hour);
 74     mins = checkTime(mins);
 75     sec = checkTime(sec);
 76     
 77     var result = hour + ":" + mins + ":" + sec;
 78     currentTime = result;
 79     document.getElementById("time").innerHTML = result.big();
 80     console.log(result);
 81     
 82     //每隔一段时间就重复执行这个函数,实现和setInterval相同的功能
 83     //setTimeout(showTime,500);
 84     //setTimeout("showTime()",500);
 85 }
 86 //将小于10的数字前面添加个0
 87 function checkTime(time)
 88 {
 89     if(time<10)
 90     {
 91         time = "0" + time;
 92     }
 93     return time;
 94 }
 95 
 96 
 97 
 98 //这个函数是按照间隔指定的时间来重复执行的
 99 setInterval(showTime,1000);
100 </script>
101 </body>
102 </html>