请教大神让js鼠标放上去固定，移开自动切换
请教大神让js鼠标放上去固定，移开自动切换，现在已实现自动切换，鼠标放上去也是切换，
程序代码：<script type="text/javascript">
var tt
function changeShow(num) {
number=num
number++;
if(number>3){
number=1;
}
for (var i = 1; i < 4; i++) {
document.getElementById("liTitle" + i).className = "off";
document.getElementById("ulcontent" + i).style.display = "none";
}
document.getElementById("liTitle" + num).className = "on";
document.getElementById("ulcontent" + num).style.display = "block";
}
var number=1
$(function(){
tt=setInterval(function(){
changeShow(number)
},2000)
})
</script>请高手帮忙看一下
