สอบถาม javascript event.keyCode ใส่ตัวเลข comma(,) จุด(.) อย่างเดียว

<script>
function IsNumeric(sText,obj){
	var ValidChars = "0123456789.,";
	var IsNumber=true;
	var Char;
	for (i = 0; i < sText.length && IsNumber == true; i++){   
		Char = sText.charAt(i);   
		if (ValidChars.indexOf(Char) == -1){  
			IsNumber = false;
		}
	}
	if(IsNumber==false){  
		obj.value="0";
	}
}
</script>
<input type="text" name="txt" onKeyUp="IsNumerid(this.value,this)">

<script type="text/javascript">
function CommaFormatted(amount)
{
	var delimiter = ","; // replace comma if desired
	var a = amount.split('.',2)
	var d = a[1];
	var i = parseInt(a[0]);
	if(isNaN(i)) { return ''; }
	var minus = '';
	if(i < 0) { minus = '-'; }
	i = Math.abs(i);
	var n = new String(i);
	var a = [];
	while(n.length > 3)
	{
		var nn = n.substr(n.length-3);
		a.unshift(nn);
		n = n.substr(0,n.length-3);
	}
	if(n.length > 0) { a.unshift(n); }
	n = a.join(delimiter);
	if(d.length < 1) { amount = n; }
	else { amount = n + '.' + d; }
	amount = minus + amount;
	return amount;
}
alert(CommaFormatted('10000.2345'));
</script>