function IsNumeric(strString) { // check for valid numeric strings var strValidChars = "0123456789.-"; var strChar; var blnResult = true; if (strString.length == 0) return false; // test strString consists of valid characters listed above for (i = 0; i < strString.length && blnResult == true; i++) { strChar = strString.charAt(i); if (strValidChars.indexOf(strChar) == -1) { blnResult = false; } } return blnResult; }