javascript - 如何重新制作要切换的菜单

Question

我的垂直菜单有这个脚本：

<script type="text/javascript"  
var menuids=["sidebarmenu1"]    
function initsidebarmenu(){
for (var i=0; i<menuids.length; i++){
var ultags=document.getElementById(menuids[i]).getElementsByTagName("ul")
for (var t=0; t<ultags.length; t++){
ultags[t].parentNode.getElementsByTagName("a")[0].className+=" subfolderstyle"
if (ultags[t].parentNode.parentNode.id==menuids[i]) 
ultags[t].style.left=ultags[t].parentNode.offsetWidth+"px" //dynamically position first level submenus to be width of main menu item
else //else if this is a sub level submenu (ul)
ultags[t].style.left=ultags[t-1].getElementsByTagName("a")[0].offsetWidth+"px" //position menu to the right of menu item that activated it
ultags[t].parentNode.onmouseover=function(){
this.getElementsByTagName("ul")[0].style.display="block"
}
ultags[t].parentNode.onmouseout=function(){
this.getElementsByTagName("ul")[0].style.display="none"
}
}
for (var t=ultags.length-1; t>-1; t--){
ultags[t].style.visibility="visible"
ultags[t].style.display="none"
}
}
}
if (window.addEventListener)
window.addEventListener("load", initsidebarmenu, false)
else if (window.attachEvent)
window.attachEvent("onload", initsidebarmenu)

</script>

我在哪里可以使用 onclick 事件来切换它，比如当我第一次按下它出现时，当我按下第二次它消失等等......？