JavaScript IsNumeric()

function isNumeric(vTestValue)
{
	// put the TEST value into a string object variable
	var sField = new String(Trim(vTestValue));
	
	// check for a length of 0 - if so, return false
	if(sField.length==0) { return false; }
	else if(sField.length==1 && (sField.charAt(0) == '.' || sField.charAt(0) == ',' || (sField.charAt(0) == '-'))) { return false; }
	
	// loop through each character of the string
	for(var x=0; x < sField.length; x++) {
		// if the character is < 0 or > 9, return false (not a number)
		if((sField.charAt(x) >= '0' && sField.charAt(x) <= '9') || sField.charAt(x) == '.' || sField.charAt(x) == ',' || (sField.charAt(x) == '-' && x==0)) { /* do nothing */ }
		else { return false; }
	}
	
	// made it through the loop - we have a number
	return true;
}