function clear(div){
	if(div.value==0){
		div.value = '';
	}
}

function zero(div){
	if(div.value==''){
		div.value = '0';
	}
}

/*Dustin Diaz I think - modified by James Hallam (TJS) */
function getElementsByClass(searchClass,type,parent) {
	var classList = new Array();
	if (typeof parent == "undefined") {
		var els = document.getElementsByTagName(type);
	} else {
		parentElem = document.getElementById(parent);
		var els = parentElem.getElementsByTagName(type);
	}
	
	var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");
	j=0;
	for (i = 0, l=els.length; i<l; i++) {
		if ( pattern.test(els[i].className) ) {
			classList[j] = els[i];
			j++;
		}
	}
	return classList;
}

/***********************************************************
* Set up the links in the page with their onblur and onsubmit handlers
************************************************************/  
function preparePage(){
	var emptyInputs = getElementsByClass('empty','input');
	
	for (var i=0; i < emptyInputs.length; i++){
		emptyInputs[i].onclick = function(){
			return clear(this);
		}
		
		emptyInputs[i].onblur = function(){
			return zero(this);
		}
	}
	
	//var addForm = getElementsByClass('addform','form');
	var addForm = document.getElementById('addform');

	if(addForm){
		addForm.onsubmit = function(){
			var valid = false;
			inputs = getElementsByClass('empty','input',addForm.id);
			for (var j=0; j < inputs.length; j++){
				if(inputs[j].value!='0'){
					valid = true;
				}
			}
			
			if(!valid){
				alert('Please add at least one product');
				return false;
			} else {
				return true;
			}
		}
	}
}
	
window.onload = preparePage;