就setInterval()方法写了个小DEMO，一个时钟显示，结合了Date类型的API。
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk">
<title>Insert title here</title>
<script type="text/javascript">
function testSetInterval(){
setInterval(clock,1000);
}
function clock(){
var time = new Date();
var hour = time.getHours();
var minute = time.getMinutes();
var second = time.getSeconds();
var year = time.getYear();
var month = time.getMonth();
var day = time.getDay();
var yearDiv = document.getElementById('year');
yearDiv.innerHTML = year;
var monthDiv = document.getElementById('month');
monthDiv.innerHTML = month;
var dayDiv = document.getElementById('day');
dayDiv.innerHTML = day;
var hourDiv = document.getElementById('hour');
hourDiv.innerHTML = hour;
var minuteDiv = document.getElementById('minute');
minuteDiv.innerHTML = minute;
var secondDiv = document.getElementById('second');
secondDiv.innerHTML = second;
}
</script>
</head>
<body onload="testSetInterval()">
<span id="year"></span>年<span id="month"></span>月<span id="day"></span>日 <span id="hour"></span>:<span id="minute"></span>:<span id="second"></span>
</body>
</html>
很麻烦，要把年月日时分秒全球一遍。汗呀，忽然发现Date类有一个tolocaleString()方法，马上应用，简单利落呀！
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk">
<title>Insert title here</title>
<script type="text/javascript">
function testSetInterval(){
setInterval(clock,1000);
}
function clock(){
var date = document.getElementById('date');
date.innerHTML = new Date().toLocaleString();
}
</script>
</head>
<body onload="testSetInterval()">
<div id="date"></div>
</body>
</html>
利用setInterval(clock,1000);每隔1秒钟调用clock方法更新页面组件值。达到时钟的效果。
实际上setInterval方法还有许多用法，举例说明
有以下两种重载形式
setIntervar(methodname,interval)
setIntervar("methodname(arg1,arg2)",interval)
setIntervar("objname.methodname(arg1,arg2)",interval);
看下面例子：
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk">
<title>Insert title here</title>
<script type="text/javascript">
function setObjInterval(){
this.warn = function(warninginfo,times){
alert('warninginfo is ' + warninginfo + 'and times is '+times);
}
}
var objInterval = new setObjInterval();
//测试调用对象的方法
function testSetObjInterval(){
setInterval("objInterval.warn('time is over', 33)", 2000);
}
function testSetInterval(){
setInterval(clock,1000);
}
function clock(){
var date = document.getElementById('date');
date.innerHTML = new Date().toLocaleString();
}
function setIntervalManyArg(){
setInterval("showInfo('shl',22)", 2000);
}
function showInfo(name){
alert('name is ' + name + ' and age is ' + age);
}
</script>
</head>
<body onload="testSetInterval()">
<div id="date"></div>
<input type='button' value="click me" onclick='testSetObjInterval()'/>
</body>
</html>