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Javascript numeric validation (See related posts)

I've seen a lot of takes on numeric validation, and most have serious flaws. For example, (!isNaN) returns inconsistent results and shouldn't be used to verify numericality. This should cover all cases, and supports a decimal point as well as negative numbers.

   1  
   2  function isNumeric(value) {
   3    if (value == null || !value.toString().match(/^[-]?\d*\.?\d*$/)) return false;
   4    return true;
   5  }


This logic is straight-forward: if the parameter isn't null, convert it to a string and match it against a RegEx to throw out false cases. Otherwise, return true.
to javascript validation by leftist on Mon Jan 29 06:37:31 -0500 2007

Comments on this post

aamirafridi posts on Jul 23, 2008 at 11:52
It can be done also as:

   1  
   2  function IsNumeric(strString) //  check for valid numeric strings	
   3  {
   4  	if(!/\D/.test(strString)) return true;//IF NUMBER
   5  	else if(/^\d+\.\d+$/.test(strString)) return true;//IF A DECIMAL NUMBER HAVING AN INTEGER ON EITHER SIDE OF THE DOT(.)
   6  	else return false;
   7  }

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