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);">
