开启定时器：单位是1000毫秒 1000毫秒=1秒 每隔一秒弹出窗口 无限执行
setInterval() 间隔型
function show(){
alert('1');
}
setInterval(show,1000);
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setTimeout 延时型：只执行一次
function show(){
alert('1');
}
setTimeout(show,1000);
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关闭定时器：
clearInterval 关闭间隔型定时器
clearTimeout 关闭延时型定时器
window.onload=function(){
var aBtn=document.getElementById('btn1');
var bBtn=document.getElementById('btn2');
var timer=null;
aBtn.onclick=function(){
timer=setInterval(function(){alert('a')},1000);
};
bBtn.onclick=function(){
clearInterval(timer);
};
};
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>QQ头像鼠标放置效果</title>
<style>
div{float:left;margin:10px;}
#div1{
50px;
height:50px;
background:#F00;
}
#div2{250px;
height:280px;
background:#666;
}
</style>
<script>
window.onload=function(){
var a=document.getElementById('div1');
var b=document.getElementById('div2');
var timer=null;
a.onmouseover=function(){
clearTimeout(timer);
b.style.display='block';
};
a.onmouseout=function(){
timer=setTimeout(function(){
b.style.display='none';
},500);
};
b.onmouseover=function(){
clearTimeout(timer);
};
/
b.onmouseout=function(){
setTimeout(function(){
b.style.display='none';
};
},500;
};
</script>
<body>
<div id="div1"></div>
<div id="div2"></div>
</body>
</html>
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