//How to Create an Animated, Sliding, Collapsible DIV with Javascript and CSS
//via Harry Maugans (http://www.harrymaugans.com/2007/03/06/how-to-create-an-animated-sliding-collapsible-div-with-javascript-and-css/)

//These are the variables you will change if you want to tweak the speed of the animation on your site.
var timerlen = 5;	//how often the Javascript function will run to alter the DIV’s properties
var slideAniLen = 250;	//how long it should take a DIV to completely slide up or completely slide down (in miliseconds)

var timerID = new Array();
var startTime = new Array();
var obj = new Array();
var endHeight = new Array();
var moving = new Array();
var dir = new Array();

//This code adds the functions to call when requesting a DIV start sliding up or down.
function toggleSlide(objname){
	if(document.getElementById(objname).style.display == "none"){
		// div is hidden, so let's slide down
		slidedown(objname);
	}else{
		// div is not hidden, so slide up
		slideup(objname);
	}
}

function slidedown(objname){
	if(moving[objname])
		return;
	if(document.getElementById(objname).style.display != "none")
		return; // cannot slide down something that is already visible

	moving[objname] = true;
	dir[objname] = "down";
	startslide(objname);
}

function slideup(objname){
	if(moving[objname])
		return;

	if(document.getElementById(objname).style.display == "none")
		return; // cannot slide up something that is already hidden

	moving[objname] = true;
	dir[objname] = "up";
	startslide(objname);
}

//This function, startslide(), is where we actually begin the sliding process.
function startslide(objname){
	obj[objname] = document.getElementById(objname);

	endHeight[objname] = parseInt(obj[objname].style.height);
	startTime[objname] = (new Date()).getTime();

	if(dir[objname] == "down"){
		obj[objname].style.height = "1px";
	}

	obj[objname].style.display = "block";

	timerID[objname] = setInterval('slidetick(\'' + objname + '\');',timerlen);
}

//This function is what actually does the animation itself.
function slidetick(objname){
	var elapsed = (new Date()).getTime() - startTime[objname];

	if (elapsed > slideAniLen)
		endSlide(objname)
	else {
		var d =Math.round(elapsed / slideAniLen * endHeight[objname]);
		if(dir[objname] == "up")
			d = endHeight[objname] - d;
		obj[objname].style.height = d + "px";
	}

	return;
}

//This is the function that’s called when the time runs out on an animation.
function endSlide(objname){
	clearInterval(timerID[objname]);
	
	if(dir[objname] == "up")
					obj[objname].style.display = "none";
	
	obj[objname].style.height = endHeight[objname] + "px";
	
	delete(moving[objname]);
	delete(timerID[objname]);
	delete(startTime[objname]);
	delete(endHeight[objname]);
	delete(obj[objname]);
	delete(dir[objname]);
	
	return;
}