var isIE = document.all?true:false;
var isNS = document.layers?true:false;

function onlyDigits(e) {
	var key = (isIE) ? window.event.keyCode : e.which;
	var obj = (isIE) ? event.srcElement : e.target;
	var isNum = (key > 47 && key < 58) ? true:false;	
	if(key < 32) return true;
	return (isNum);
}

function numbersOnly(){
	var fields = document.getElementsByTagName('input');
	for(var i=0; i<fields.length; i++){
		if(fields[i].getAttribute('type')=='text'){
			addEvent(fields[i],'keypress',onlyDigits);
		}
	}
}

function checkValue(obj){
	if(document.getElementById(obj)){
		var obj = document.getElementById(obj);
		var expr = new RegExp(/^[0-9]+$/);
		return (expr.test(obj.value))?parseInt(obj.value):0;
	}else{
		return 0;
	}
}