调用方法：
<body onload="startTime()"> <div id="time"></div> </body>/* 动态显示时间 函数*/
function startTime() {
var today = new Date();
var y = today.getFullYear();
var M = today.getMonth() + 1;
var d = today.getDate();
var h = today.getHours();
var m = today.getMinutes();
var s = today.getSeconds();
var w = today.getDay();
var weekday = new Array(7);
weekday[0] = "星期日";
weekday[1] = "星期一";
weekday[2] = "星期二";
weekday[3] = "星期三";
weekday[4] = "星期四";
weekday[5] = "星期五";
weekday[6] = "星期六";
// 当分钟和秒为个位数时前面补0
if (m < 10) {
m = "0" + m;
}
if (s < 10) {
s = "0" + s;
}
document.getElementById('time').innerHTML = y + "-" + M + "-" + d + " " + h
+ ":" + m + ":" + s + " " + weekday[w];
var t = setTimeout(function() {
startTime()
}, 500); /* 每500毫秒执行一次，实现动态显示时间效果 */
}