Any Javascript experts??? *Strange* problem - please help!!!!

[slylittlefox]

Evening all,

I recently spent a couple of weeks developing a site for my dad, which has now gone live. (www.drainbrains.co.uk)

However, one of the bits of script I've used on this page creates a severe problem - it somehow generates ~3500 DOM elements, which after a couple of visits within Firefox crashes the entire browser.

I've stared at the code (shown below) for a couple of days, but I can't see how it's causing the problem.

/* 

	List Expander 
	written by Alen Grakalic, provided by Css Globe (cssglobe.com)
	
*/

this.listexpander = function(){
	
	// edit 
	
	var expandTo = 1; // level up to which you want your lists to be initially expanded. 1 is minimum
	var expandText = "Expand All"; // text for expand all button
	var collapseText = "Collapse All"; // text for collapse all button		
	var listClass = "listexpander" // class name that you want to assign to list(s). If you wish to change it make sure to update the css file as well  
	
	// end edit (do not edit below this line)
	
	this.start = function(){
		var ul = document.getElementsByTagName("ul");
		for (var i=0;i<ul.length;i++){
			if(ul[i].className == listClass){
				create(ul[i]);
				buttons(ul[i])
			};
		};
	};

	this.create = function(list) {	
		var items = list.getElementsByTagName("li");
		for(var i=0;i<items.length;i++){
			listItem(items[i]);
		};
	};	

	this.listItem = function(li){
		if(li.getElementsByTagName("ul").length > 0){
			var ul = li.getElementsByTagName("ul")[0];
			ul.style.display = (depth(ul) <= expandTo) ? "block" : "none";
			li.className = (depth(ul) <= expandTo) ? "expanded" : "collapsed";
			li.over = true;	
			ul.onmouseover = function(){li.over = false;} 
			ul.onmouseout = function(){li.over = true;} 
			li.onclick = function(){
				if(this.over){
					ul.style.display = (ul.style.display == "none") ? "block" : "none";
					this.className = (ul.style.display == "none") ? "collapsed" : "expanded";				
				};
			};
		};		
	};	
	
	this.buttons = function(list){
		var parent = list.parentNode;
		var p = document.createElement("p");
		p.className = listClass;
		var a = document.createElement("a");
		a.innerHTML = expandText;
		a.onclick = function(){expand(list)};
		p.appendChild(a);
		var a = document.createElement("a");
		a.innerHTML = collapseText;
		a.onclick = function(){collapse(list)};
		p.appendChild(a);
		parent.insertBefore(p,list);
	};
	
	this.expand = function(list){
		li = list.getElementsByTagName("li");
		for(var i=0;i<li.length;i++){
			if(li[i].getElementsByTagName("ul").length > 0){
				var ul = li[i].getElementsByTagName("ul")[0];
				ul.style.display = "block";
				li[i].className = "expanded";
			};
		};
	};
	
	this.collapse = function(list){
		li = list.getElementsByTagName("li");
		for(var i=0;i<li.length;i++){
			if(li[i].getElementsByTagName("ul").length > 0){
				var ul = li[i].getElementsByTagName("ul")[0];
				ul.style.display = "none";
				li[i].className = "collapsed";
			};
		};
	};
	
	this.depth = function(obj){
		var level = 1;
		while(obj.parentNode.className != listClass){
			if (obj.tagName == "UL") level++;
			obj = obj.parentNode;
		};
		return level;
	};	
	
	start();
	
};

window.onload = listexpander;

I've e-mailed the author but sadly haven't heard back from him.

Any ideas or suggestions as to how it could be causing this problem would be greatly appreciated!

Most of the other browsers seem to cope (albeit they slow down), but Firefox generally crashes upon the second visit to that page. (If you're not convinced, keep navigating around the site, on to that page and away from it.)