AnyLink JS Drop Down Menu

<link rel="stylesheet" type="text/css" href="anylinkmenu.css" />

<script type="text/javascript">
var anylinkmenu1={divclass:'anylinkmenu', inlinestyle:'', linktarget:''} //First menu variable. Make sure "anylinkmenu1" is a unique name!
anylinkmenu1.items=[
["Dynamic Drive", "http://www.dynamicdrive.com/"],
["CSS Drive", "http://www.cssdrive.com/"],
["JavaScript Kit", "http://www.javascriptkit.com/"],
["Coding Forums", "http://www.codingforums.com/"],
["JavaScript Reference", "http://www.javascriptkit.com/jsref/"] //no comma following last entry!
]



var anylinkmenu2={divclass:'anylinkmenu', inlinestyle:'width:150px; background:#FDD271', linktarget:'_new'} //Second menu variable. Same precaution.
anylinkmenu2.items=[
["CNN", "http://www.cnn.com/"],
["MSNBC", "http://www.msnbc.com/"],
["Google", "http://www.google.com/"],
["BBC News", "http://news.bbc.co.uk"] //no comma following last entry!
]



var anylinkmenu3={divclass:'anylinkmenucols', inlinestyle:'', linktarget:'secwin'} //Third menu variable. Same precaution.
anylinkmenu3.cols={divclass:'column', inlinestyle:''} //menu.cols if defined creates columns of menu links segmented by keyword "efc"
anylinkmenu3.items=[
["Dynamic Drive", "http://www.dynamicdrive.com/"],
["CSS Drive", "http://www.cssdrive.com/"],
["JavaScript Kit", "http://www.javascriptkit.com/"],
["Coding Forums", "http://www.codingforums.com/"],
["JavaScript Reference", "http://www.javascriptkit.com/jsref/", "efc"],
["CNN", "http://www.cnn.com/"],
["MSNBC", "http://www.msnbc.com/"],
["Google", "http://www.google.com/"],
["BBC News", "http://news.bbc.co.uk", "efc"],
["News.com", "http://www.news.com/"],
["SlashDot", "http://www.slashdot.com/"],
["Digg", "http://www.digg.com/"],
["Tech Crunch", "http://techcrunch.com"] //no comma following last entry!
]

</script>

<script type="text/javascript" src="anylinkmenu.js">

//** AnyLink JS Drop Down Menu v2.0- (c) Dynamic Drive DHTML code library: http://www.dynamicdrive.com
//** Script Download/ instructions page: http://www.dynamicdrive.com/dynamicindex1/dropmenuindex.htm
//** January 29th, 2009: Script Creation date

var anylinkmenu={

menusmap: {},
effects: {delayhide: 200, shadow:{enabled:true, opacity:0.3, depth: [5, 5]}, fade:{enabled:false, duration:500}}, //customize menu effects

dimensions: {},

getoffset:function(what, offsettype){
return (what.offsetParent)? what[offsettype]+this.getoffset(what.offsetParent, offsettype) : what[offsettype]
},

getoffsetof:function(el){
el._offsets={left:this.getoffset(el, "offsetLeft"), top:this.getoffset(el, "offsetTop"), h: el.offsetHeight}
},

getdimensions:function(menu){
this.dimensions={anchorw:menu.anchorobj.offsetWidth, anchorh:menu.anchorobj.offsetHeight,
docwidth:(window.innerWidth ||this.standardbody.clientWidth)-20,
docheight:(window.innerHeight ||this.standardbody.clientHeight)-15,
docscrollx:window.pageXOffset || this.standardbody.scrollLeft,
docscrolly:window.pageYOffset || this.standardbody.scrollTop
}
if (!this.dimensions.dropmenuw){
this.dimensions.dropmenuw=menu.dropmenu.offsetWidth
this.dimensions.dropmenuh=menu.dropmenu.offsetHeight
}
},

isContained:function(m, e){
var e=window.event || e
var c=e.relatedTarget || ((e.type=="mouseover")? e.fromElement : e.toElement)
while (c && c!=m)try {c=c.parentNode} catch(e){c=m}
if (c==m)
return true
else
return false
},

setopacity:function(el, value){
el.style.opacity=value
if (typeof el.style.opacity!="string"){ //if it's not a string (ie: number instead), it means property not supported
el.style.MozOpacity=value
if (el.filters){
el.style.filter="progid:DXImageTransform.Microsoft.alpha(opacity="+ value*100 +")"
}
}
},

showmenu:function(menuid){
var menu=anylinkmenu.menusmap[menuid]
clearTimeout(menu.hidetimer)
this.getoffsetof(menu.anchorobj)
this.getdimensions(menu)
var posx=menu.anchorobj._offsets.left + (menu.orientation=="lr"? this.dimensions.anchorw : 0) //base x pos
var posy=menu.anchorobj._offsets.top+this.dimensions.anchorh - (menu.orientation=="lr"? this.dimensions.anchorh : 0)//base y pos
if (posx+this.dimensions.dropmenuw+this.effects.shadow.depth[0]>this.dimensions.docscrollx+this.dimensions.docwidth){ //drop left instead?
posx=posx-this.dimensions.dropmenuw + (menu.orientation=="lr"? -this.dimensions.anchorw : this.dimensions.anchorw)
}
if (posy+this.dimensions.dropmenuh>this.dimensions.docscrolly+this.dimensions.docheight){  //drop up instead?
posy=Math.max(posy-this.dimensions.dropmenuh - (menu.orientation=="lr"? -this.dimensions.anchorh : this.dimensions.anchorh), this.dimensions.docscrolly) //position above anchor or window's top edge
}
if (this.effects.fade.enabled){
this.setopacity(menu.dropmenu, 0) //set opacity to 0 so menu appears hidden initially
if (this.effects.shadow.enabled)
this.setopacity(menu.shadow, 0) //set opacity to 0 so shadow appears hidden initially
}
menu.dropmenu.setcss({left:posx+'px', top:posy+'px', visibility:'visible'})
if (this.effects.shadow.enabled){
//menu.shadow.setcss({width: menu.dropmenu.offsetWidth+"px", height:menu.dropmenu.offsetHeight+"px"})
menu.shadow.setcss({left:posx+anylinkmenu.effects.shadow.depth[0]+'px', top:posy+anylinkmenu.effects.shadow.depth[1]+'px', visibility:'visible'})
}
if (this.effects.fade.enabled){
clearInterval(menu.animatetimer)
menu.curanimatedegree=0
menu.starttime=new Date().getTime() //get time just before animation is run
menu.animatetimer=setInterval(function(){anylinkmenu.revealmenu(menuid)}, 20)
}
},

revealmenu:function(menuid){
var menu=anylinkmenu.menusmap[menuid]
var elapsed=new Date().getTime()-menu.starttime //get time animation has run
if (elapsed<this.effects.fade.duration){
this.setopacity(menu.dropmenu, menu.curanimatedegree)
if (this.effects.shadow.enabled)
this.setopacity(menu.shadow, menu.curanimatedegree*this.effects.shadow.opacity)
}
else{
clearInterval(menu.animatetimer)
this.setopacity(menu.dropmenu, 1)
menu.dropmenu.style.filter=""
}
menu.curanimatedegree=(1-Math.cos((elapsed/this.effects.fade.duration)*Math.PI)) / 2
},

setcss:function(param){
for (prop in param){
this.style[prop]=param[prop]
}
},

hidemenu:function(menuid){
var menu=anylinkmenu.menusmap[menuid]
clearInterval(menu.animatetimer)
menu.dropmenu.setcss({visibility:'hidden', left:0, top:0})
menu.shadow.setcss({visibility:'hidden', left:0, top:0})
},

getElementsByClass:function(targetclass){
if (document.querySelectorAll)
return document.querySelectorAll("."+targetclass)
else{
var classnameRE=new RegExp("(^|\\s+)"+targetclass+"($|\\s+)", "i") //regular expression to screen for classname
var pieces=[]
var alltags=document.all? document.all : document.getElementsByTagName("*")
for (var i=0; i<alltags.length; i++){
if (typeof alltags[i].className=="string" && alltags[i].className.search(classnameRE)!=-1)
pieces[pieces.length]=alltags[i]
}
return pieces
}
},

addDiv:function(divid, divclass, inlinestyle){
var el=document.createElement("div")
if (divid)
el.id=divid
el.className=divclass
if (inlinestyle!="" && typeof el.style.cssText=="string")
el.style.cssText=inlinestyle
else if (inlinestyle!="")
el.setAttribute('style', inlinestyle)
document.body.appendChild(el)
return el
},

getmenuHTML:function(menuobj){
var menucontent=[]
var frag=""
for (var i=0; i<menuobj.items.length; i++){
frag+='<li><a href="' + menuobj.items[i][1] + '" target="' + menuobj.linktarget + '">' + menuobj.items[i][0] + '</a></li>\n'
if (menuobj.items[i][2]=="efc" || i==menuobj.items.length-1){
menucontent.push(frag)
frag=""
}
}
if (typeof menuobj.cols=="undefined")
return '<ul>\n' + menucontent.join('') + '\n</ul>'
else{
frag=""
for (var i=0; i<menucontent.length; i++){
frag+='<div class="' + menuobj.cols.divclass + '" style="' + menuobj.cols.inlinestyle + '">\n<ul>\n' + menucontent[i] + '</ul>\n</div>\n'
}
return frag
}
},

addEvent:function(targetarr, functionref, tasktype){
if (targetarr.length>0){
var target=targetarr.shift()
if (target.addEventListener)
target.addEventListener(tasktype, functionref, false)
else if (target.attachEvent)
target.attachEvent('on'+tasktype, function(){return functionref.call(target, window.event)})
this.addEvent(targetarr, functionref, tasktype)
}
},

setupmenu:function(targetclass, anchorobj, pos){
this.standardbody=(document.compatMode=="CSS1Compat")? document.documentElement : document.body
var relattr=anchorobj.getAttribute("rel")
dropmenuid=relattr.replace(/\[(\w+)\]/, '')
var dropmenuvar=window[dropmenuid]
var dropmenu=this.addDiv(null, dropmenuvar.divclass, dropmenuvar.inlinestyle) //create and add main sub menu DIV
dropmenu.innerHTML=this.getmenuHTML(dropmenuvar)
var menu=this.menusmap[targetclass+pos]={
id: targetclass+pos,
anchorobj: anchorobj,
dropmenu: dropmenu,
revealtype: (relattr.length!=dropmenuid.length && RegExp.$1=="click")? "click" : "mouseover",
orientation: anchorobj.getAttribute("rev")=="lr"? "lr" : "ud",
shadow: this.addDiv(null, "anylinkshadow", null) //create and add corresponding shadow
}
menu.anchorobj._internalID=targetclass+pos
menu.anchorobj._isanchor=true
menu.dropmenu._internalID=targetclass+pos
menu.shadow._internalID=targetclass+pos
menu.dropmenu.setcss=this.setcss
menu.shadow.setcss=this.setcss
menu.shadow.setcss({width: menu.dropmenu.offsetWidth+"px", height:menu.dropmenu.offsetHeight+"px"})
this.setopacity(menu.shadow, this.effects.shadow.opacity)
this.addEvent([menu.anchorobj, menu.dropmenu, menu.shadow], function(e){ //MOUSEOVER event for anchor, dropmenu, shadow
var menu=anylinkmenu.menusmap[this._internalID]
if (this._isanchor && menu.revealtype=="mouseover" && !anylinkmenu.isContained(this, e)){ //event for anchor
anylinkmenu.showmenu(menu.id)
}
else if (typeof this._isanchor=="undefined"){ //event for drop down menu and shadow
clearTimeout(menu.hidetimer)
}
}, "mouseover")
this.addEvent([menu.anchorobj, menu.dropmenu, menu.shadow], function(e){ //MOUSEOUT event for anchor, dropmenu, shadow
if (!anylinkmenu.isContained(this, e)){
var menu=anylinkmenu.menusmap[this._internalID]
menu.hidetimer=setTimeout(function(){anylinkmenu.hidemenu(menu.id)}, anylinkmenu.effects.delayhide)
}
}, "mouseout")
this.addEvent([menu.anchorobj, menu.dropmenu], function(e){ //CLICK event for anchor, dropmenu
var menu=anylinkmenu.menusmap[this._internalID]
if ( this._isanchor && menu.revealtype=="click"){
if (menu.dropmenu.style.visibility=="visible")
anylinkmenu.hidemenu(menu.id)
else
anylinkmenu.showmenu(menu.id)
if (e.preventDefault)
e.preventDefault()
return false
}
else
menu.hidetimer=setTimeout(function(){anylinkmenu.hidemenu(menu.id)}, anylinkmenu.effects.delayhide)
}, "click")
},

init:function(targetclass){
var anchors=this.getElementsByClass(targetclass)
for (var i=0; i<anchors.length; i++){
this.setupmenu(targetclass, anchors[i], i)
}
}

}

</script>
<!--1st anchor link-->

<p><a href="http://www.dynamicdrive.com" class="menuanchorclass" rel="anylinkmenu1">Default Example</a></p>


<!--2nd anchor link-->

<p><a href="http://www.dynamicdrive.com" class="menuanchorclass someotherclass" rel="anylinkmenu2[click]" rev="lr">Right dropping menu</a> (click to reveal)</p>
                                                   

<!--3rd anchor link-->

<p style="text-align:center"><a href="http://www.dynamicdrive.com" class="menuanchorclass myownclass" rel="anylinkmenu3">Menu with multiple columns</a></p>
                                                   




<script type="text/javascript">

//anylinkmenu.init("menu_anchors_class") //call this function at the very *end* of the document!
anylinkmenu.init("menuanchorclass")
</script>
来自：http://www.dynamicdrive.com/dynamicindex1/dropmenuindex.htm