用Js实现实时显示系统时间

今天看到时钟，想着也用网页简单的实现一下，以下是实现效果：

以下是代码实现：

Html实现，将JS添加进去

 <h1>Today is <span id="dtField"></span>.</h1>

js代码实现

window.onload = initDate;
function initDate() {
var dayName = new Array("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday");
var monName = new Array("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December");

var now = new Date();
var dtString = dayName[now.getDay()] + "," + monName[now.getMonth()] + " " + now.getDate() + " " + now.getHours()
+ ":"+now.getMinutes()+":"+now.getSeconds();

document.getElementById("dtField").innerHTML = dtString;
setInterval("initDate()",1000);
}