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Tip of the Day
Language: JavaScript
Expertise: Intermediate
Oct 17, 2006

Determine Whether a Value is Numeric

JavaScript has a built-in function called isNAN that can be used to check if a value is numeric or not.

The isNan function returns true if the value is not numeric, and false if it is numeric:


function chkDigits(obj)
{
   if (isNaN(document.getElementById(obj).value)==true)
   {
    alert("Please enter digits");
    document.getElementById(obj).focus();
    document.getElementById(obj).select();
    return false;
  }
}
Here's how to call it:

<input id="Textbox1" value="ddd" onblur="return chkDigits(this);">
Srinath MS
 
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