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Text box to accept only number

, 23 Apr 2011 CPOL
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Text box to accept only number
   <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;
      <INPUT id="txtChar" onkeypress="return isNumberKey(event)" type="text" name="txtChar">

Just paste the Script Section in the Head section and in on key press call the function.
For C#, just paste the following code:

function allownumbers(e) {
        var key = window.event ? e.keyCode : e.which;
        var keychar = String.fromCharCode(key);
        var reg = new RegExp("[0-9.]")
        if (key == 8) {
            keychar = String.fromCharCode(key);

And in PageLoad:
txtNum.Attributes.Add("onkeypress", "javascript:return allownumbers(event);");


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

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I am Prasanta Banerjee. I am an Asp.Net Developer. My site:
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Comments and Discussions

QuestionGood Solution PinmemberAlireza_136220-Mar-13 23:24 
GeneralMy vote of 2 Pinmemberniubay11-Sep-12 4:31 
GeneralRe: by small digits I mean something like: 1.2345, 6.78 etc I ... PinmemberUnruled Boy24-Apr-11 13:14 
GeneralRe: Agreed. Something like this regular expression /^-?[0-9]+(\.... Pinmemberdanlobo30-Dec-11 0:32 
GeneralRe: Negative values you just have to program to allow the minus ... PinmemberEdMan19624-Apr-11 4:08 
GeneralRe: The keyboard remapping just assigns different characters to ... PinprotectorAspDotNetDev24-Apr-11 1:44 
GeneralRe: For starters you can remap your keyboard but also, the world... PinmemberEdMan19623-Apr-11 23:57 
For starters you can remap your keyboard but also, the world isn't just ASCII you know, there's UTF-8 etc. Also, how about my sister's Russian keyboard that is completely different, I would doubt that that maps exactly the same. Perhaps the numbers might be the same but as a general rule, use chars, it's safer.
GeneralReason for my vote of 5 exclent Pinmemberlovepreet_shota18-Jun-11 18:15 
GeneralThis is all well and good unless of course my keyboards numb... PinmemberEdMan19623-Apr-11 3:40 
GeneralRe: What do you mean? How would your keyboard number keys use di... PinprotectorAspDotNetDev23-Apr-11 19:51 
GeneralRe: what if small digits or negative values? I think using regex... PinmemberUnruled Boy24-Apr-11 4:05 
GeneralExplanation needed PinsubeditorIndivara18-Apr-11 13:05 
GeneralRe: Explanation needed Pinmemberpashad27-Dec-11 19:52 

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