How to find if argument is numeric or not, using Javascript

Use the code below:

// checks to see whether the input is a numeric string or not also includes "." and "-"
function IsNumeric(strString)
	var strValidChars = "0123456789.-"; // valid characters for a numeric string
	var strChar;
	var result = true;
	var i = 0
	if (strString.length == 0) return false;
	// check to see if strString consists of valid characters listed in strValidChars
	while (i < strString.length && result == true)
		strChar = strString.charAt(i);
		if (strValidChars.indexOf(strChar) == -1) return false;
	return result;

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