javascript处理层(DIV)的下拉

这都是来自http://www.dynamicdrive.com的
js的内容:

//Animated Collapsible DIV- Author: Dynamic Drive (http://www.dynamicdrive.com)
//Last updated Aug 1st, 07'. Fixed bug with "block" parameter not working when persist is enabled
//Updated June 27th, 07'. Added ability for a DIV to be initially expanded.

var uniquepageid=window.location.href.replace("http://"+window.location.hostname, "").replace(/^\//, "") //get current page path and name, used to uniquely identify this page for persistence feature

//divId:层的id ; animatetime下拉或收缩的时间 ；persistexpand＝true/false,false表示开始状态是收缩,除非initstate为"block";initstate初始状态this.initstate=(typeof initstate!="undefined" && initstate=="block")? "block" : "contract"
function animatedcollapse(divId, animatetime, persistexpand, initstate){
	this.divId=divId
	this.divObj=document.getElementById(divId)
	this.divObj.style.overflow="hidden"
	this.timelength=animatetime
	this.initstate=(typeof initstate!="undefined" && initstate=="block")? "block" : "contract"
	this.isExpanded=animatedcollapse.getCookie(uniquepageid+"-"+divId) //"yes" or "no", based on cookie value
	this.contentheight=parseInt(this.divObj.style.height)
	var thisobj=this
	if (isNaN(this.contentheight)){ //if no CSS "height" attribute explicitly defined, get DIV's height on window.load
		animatedcollapse.dotask(window, function(){thisobj._getheight(persistexpand)}, "load")
		if (!persistexpand && this.initstate=="contract" || persistexpand && this.isExpanded!="yes" && this.isExpanded!="") //Hide DIV (unless div should be expanded by default, OR persistence is enabled and this DIV should be expanded)
			this.divObj.style.visibility="hidden" //hide content (versus collapse) until we can get its height
	}
	else if (!persistexpand && this.initstate=="contract" || persistexpand && this.isExpanded!="yes" && this.isExpanded!="") //Hide DIV (unless div should be expanded by default, OR persistence is enabled and this DIV should be expanded)
		this.divObj.style.height=0 //just collapse content if CSS "height" attribute available
	if (persistexpand)
		animatedcollapse.dotask(window, function(){animatedcollapse.setCookie(uniquepageid+"-"+thisobj.divId, thisobj.isExpanded)}, "unload")
}

animatedcollapse.prototype._getheight=function(persistexpand){
	this.contentheight=this.divObj.offsetHeight
	if (!persistexpand && this.initstate=="contract" || persistexpand && this.isExpanded!="yes"){ //Hide DIV (unless div should be expanded by default, OR persistence is enabled and this DIV should be expanded)
		this.divObj.style.height=0 //collapse content
		this.divObj.style.visibility="visible"
	}
	else //else if persistence is enabled AND this content should be expanded, define its CSS height value so slideup() has something to work with
		this.divObj.style.height=this.contentheight+"px"
}


animatedcollapse.prototype._slideengine=function(direction){
	var elapsed=new Date().getTime()-this.startTime //get time animation has run
	var thisobj=this
	if (elapsed<this.timelength){ //if time run is less than specified length
		var distancepercent=(direction=="down")? animatedcollapse.curveincrement(elapsed/this.timelength) : 1-animatedcollapse.curveincrement(elapsed/this.timelength)
	this.divObj.style.height=distancepercent * this.contentheight +"px"
	this.runtimer=setTimeout(function(){thisobj._slideengine(direction)}, 10)
	}
	else{ //if animation finished
		this.divObj.style.height=(direction=="down")? this.contentheight+"px" : 0
		this.isExpanded=(direction=="down")? "yes" : "no" //remember whether content is expanded or not
		this.runtimer=null
	}
}


animatedcollapse.prototype.slidedown=function(){
	if (typeof this.runtimer=="undefined" || this.runtimer==null){ //if animation isn't already running or has stopped running
		if (isNaN(this.contentheight)) //if content height not available yet (until window.onload)
			alert("Please wait until document has fully loaded then click again")
		else if (parseInt(this.divObj.style.height)==0){ //if content is collapsed
			this.startTime=new Date().getTime() //Set animation start time
			this._slideengine("down")
		}
	}
}

animatedcollapse.prototype.slideup=function(){
	if (typeof this.runtimer=="undefined" || this.runtimer==null){ //if animation isn't already running or has stopped running
		if (isNaN(this.contentheight)) //if content height not available yet (until window.onload)
			alert("Please wait until document has fully loaded then click again")
		else if (parseInt(this.divObj.style.height)==this.contentheight){ //if content is expanded
			this.startTime=new Date().getTime()
			this._slideengine("up")
		}
	}
}

animatedcollapse.prototype.slideit=function(){
	if (isNaN(this.contentheight)) //if content height not available yet (until window.onload)
		alert("Please wait until document has fully loaded then click again")
	else if (parseInt(this.divObj.style.height)==0)
		this.slidedown()
	else if (parseInt(this.divObj.style.height)==this.contentheight)
		this.slideup()
}

// -------------------------------------------------------------------
// A few utility functions below:
// -------------------------------------------------------------------

animatedcollapse.curveincrement=function(percent){
	return (1-Math.cos(percent*Math.PI)) / 2 //return cos curve based value from a percentage input
}


animatedcollapse.dotask=function(target, functionref, tasktype){ //assign a function to execute to an event handler (ie: onunload)
	var tasktype=(window.addEventListener)? tasktype : "on"+tasktype
	if (target.addEventListener)
		target.addEventListener(tasktype, functionref, false)
	else if (target.attachEvent)
		target.attachEvent(tasktype, functionref)
}

animatedcollapse.getCookie=function(Name){ 
	var re=new RegExp(Name+"=[^;]+", "i"); //construct RE to search for target name/value pair
	if (document.cookie.match(re)) //if cookie found
		return document.cookie.match(re)[0].split("=")[1] //return its value
	return ""
}

animatedcollapse.setCookie=function(name, value){
		document.cookie = name+"="+value
}

实例代码:

<!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">

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

<p><b>Example 1:</b></p>

<a href="javascript:collapse1.slidedown()">Slide Down</a> || <a href="javascript:collapse1.slideup()">Slide Up</a>
<div id="dog" style="width: 300px; height: 110px; background-color: #99E0FB;">

<!--Your DIV content as follows -->
<h3>Content inside DIV!</h3>
<h4>Note: CSS height attribute defined</h4>

</div>

<script type="text/javascript">

//Syntax: var uniquevar=new animatedcollapse("DIV_id", animatetime_milisec, enablepersist(true/fase), [initialstate] )
var collapse1=new animatedcollapse("dog", 1000, false)  //false表示开始状态是收缩,如果("dog", 1000, false,"block")有"block"就默认张开

</script>



<p><b>Example 2:</b></p>

<a href="javascript:collapse2.slideit()">Show/ Hide DIV</a>
<div id="cat" style="width: 300px; background-color: #99E0FB;">

<!--Your DIV content as follows. Note to add CSS padding or margins, do it inside a DIV within the Collapsible DIV -->
<div style="padding: 0 5px">
<h3>Content inside DIV!</h3>
<h3>Content inside DIV!</h3>
<h4>Note: No CSS height attribute defined. Persistence enabled.</h4>
</div>

</div>

<script type="text/javascript">

//Syntax: var uniquevar=new animatedcollapse("DIV_id", animatetime_milisec, enablepersist(true/fase), [initialstate] )
var collapse2=new animatedcollapse("cat", 800, true)

</script>




<p><b>Example 3:</b></p>

<a href="javascript:collapse3.slidedown()">Slide Down</a> || <a href="javascript:collapse3.slideup()">Slide Up</a>
<div id="fish" style="width: 300px; height: 150px; background-color: #99E0FB;">

<!--Your DIV content as follows -->
<h3>Content inside DIV!</h3>
<h4>Note: DIV set not to collapse initially. Note that if "enablepersist" is enabled, cookie value overrides this setting.</h4>

</div>

<script type="text/javascript">

//Syntax: var uniquevar=new animatedcollapse("DIV_id", animatetime_milisec, enablepersist(true/fase), [initialstate] )
var collapse3=new animatedcollapse("fish", 1000, false, "block")

</script>