setInterval() 方法會不停地調用函數，直到 clearInterval() 被調用或窗口被關閉。由 setInterval() 返回的 ID 值可用作 clearInterval() 方法的參數。
setinterval()用法
<body>
<div id="content" style="position:relative; height:1000px; width:1000px; background-color:#666;">
<div id="one" style="position:absolute;top:0px; left:0px; height:100px; width:100px; background-color:red;"></div>
</div>
<script>
var one=document.getElementById('one')
var x=0;
var y=0;
var xs=10;
var ys=10;
function scroll(){
x+=xs;
y+=ys;
if(x>=document.getElementById('content').offsetWidth-one.offsetWidth-20 || x<=0)
{
xs=-1*xs;
}
if(y>=document.getElementById('content').offsetHeight-one.offsetHeight-20 || y<=0)
{
ys=-1*ys;
}
one.style.left=x;
one.style.top=y;
}
dt=setInterval(scroll,100);
one.onmouseover=function(){
clearInterval(dt);
};
one.onmouseout=function(){
dt=setInterval(scroll,100);
};
</script>
</body>
<form>
<input type="text" id="clock" size="35" />
<script language=javascript>
var int=self.setInterval("clock()",50)
function clock(){var t=new Date()
document.getElementById("clock").value=t
}
</script>
</form>
<div id="clock"></div>
<button onclick="int=window.clearInterval(int)">Stop interval</button>
