Allow Only Numbers in a Textbox

pradeep's Avatar author of Allow Only Numbers in a Textbox
This is an article on Allow Only Numbers in a Textbox in JavaScript and AJAX.
Sometimes we need the user to enter only numbers in a text field, so I have some up with a small piece of JavaScript to do exactly that. It works for both IE and Firefox.

Code: JavaScript
function onlyNumbers(evt)
{
    var e = event || evt; // for trans-browser compatibility
    var charCode = e.which || e.keyCode;

    if (charCode > 31 && (charCode < 48 || charCode > 57))
        return false;

    return true;

}
Example Usage:
HTML Code:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE>Allow Only Numbers
</HEAD>

<BODY>
<script language="JavaScript">
function onlyNumbers(evt)
{
	var e = event || evt; // for trans-browser compatibility
	var charCode = e.which || e.keyCode;

	if (charCode > 31 && (charCode < 48 || charCode > 57))
		return false;

	return true;

}
</script>
<input type="text" onkeypress="return onlyNumbers();">
</BODY>
</HTML>
julymaryrea_13 like this
0
vikas's Avatar, Join Date: May 2007
Light Poster
thanks for this but u must mention the comments as much as possible so that other readers could eaisily get this. thx again
0
Vivid's Avatar
Newbie Member
Is there any way to add the ability to enter in the "-" character as well. I think it is key code 109 or 189. I can't seem to get it to accept only numbers and this one extra character.
0
shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
I am not a JS expert but you need to edit the condition
Code:
if (charCode > 31 && (charCode < 48 || charCode > 57))
so that when its 109 or 189 then it does not return false.
0
pradeep's Avatar, Join Date: Apr 2005
Team Leader
Shabbir is right you just have to modify the condition to suit your needs, e.g.

Code: Javascript
if (charCode > 31 && ((charCode < 48 || charCode > 57) || charCode !=109))
  return false;

That should do it!
0
Darkness1337's Avatar, Join Date: Mar 2007
Ambitious contributor
wow, really good!
thanx a lot! this helps to get me some more marks on my web designing course lol
0
Miles Tegg's Avatar, Join Date: Aug 2008
Newbie Member
Not so smart. This doesn't allow for the shift key being pressed, so allows any of !"£$%^&*() as well as any numeric.

Obviously (??) the onKeyDown etc doesnt detect Shift1 etc.

So as a validation before assigning to a numeric field then this just doesnt work.
0
Miles Tegg's Avatar, Join Date: Aug 2008
Newbie Member

The problem with the shift key can be fixed as follows :
{
var e = event || evt; // for trans-browser compatibility
var charCode = e.which || e.keyCode;

if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
if (e.shiftkey) return false;
return true;

}
The down side of this is that it efectively disables the numeric key pay because the Num Lock sets the shift key.

You probably need to extend the numeric character set tested for to include a decimal point . or , depending upon convention, the thousand marker , and + and - to detect signs and on occasions the currency symbols such as £$ etc
0
darksemo's Avatar, Join Date: Mar 2009
Newbie Member
Helloo,
I'm not a javascript expert also, but this function has a parameter and we when we called it down , it doesn't talk any parameters . How Come?
0
gkumar's Avatar
Banned
In this example we can allow Only Numbers in a Textbox.
HTML Code:
<HTML>
   <HEAD>
   <SCRIPT language=Javascript>
      <!--
      function isNumberKey(evt)
      {
         var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (charCode < 48 || charCode > 57))
            return false;

         return true;
      }
      //-->
   </SCRIPT>
   </HEAD>
   <BODY>
      <INPUT id="txtChar" onkeypress="return isNumberKey(event)" type="text" name="txtChar">
   </BODY>
</HTML>