Develop Reference

How to make user to paste only digits into a text area box?

I have a requirement to make a textarea field allow only digits and enter keys which can be checked easily with,
function validate(key) {
// getting key code of pressed key
var keycode = (key.which) ? key.which : key.keyCode;
var phn = document.getElementById('textarea');
// comparing pressed keycodes
if ((keycode < 48 || keycode > 57) && keycode !== 13) {
return false;
}
}
<div>
<textarea id="textarea" rows="4" cols="50" onkeypress="return validate(event)" />
</div>
But this functionality breaks if the user copy-paste something into the text area field. How can I make user paste only if he has copied digits only, i.e
13131331 - should be pasted
2wewewe12 - should not be pasted
I don't do Javascript. Kindly suggest something?

jQuery for reading input of pasted string:
$input = $("textarea");
$input.on("input", function(){
var value = $(this).val();
if ( ! isNaN(parseInt(value)))
$(this).val("");
});
each time you either enter a character, OR paste something into the text area, it will check to see if the value of the text area is numeric. If it is, keep it, else dump the entire contents and make it the empty string.

Assuming inputText is the content of a input field, try:
var textareaInput = $("#txtarea").val();
if ((keycode < 48 || keycode > 57) && keycode !== 13 && isNaN(parseInt(textareaInput)))
{
return false;
}
It will return true if the input is a number.

There is a beautiful jquery plugin for that purpose: inputmask. You might like it

Alert and not allow if same word written twice in an input jquery or js

This is my input:
<input type='text' class='myprofiletags' name='my_profile_tags' value='' />
I want to alert and forbid the user if he/she writes the same word twice. I am entering values with commma e.g
games, animes, movies
jQuery('.myprofiletags').keypress(function(e)
{
if (jQuery(this).val().match(/,/g).length >= 10)
{
if(e.keyCode == 8 || e.keyCode == 46 || e.keyCode == 37 || e.keyCode == 38 || e.keyCode == 39 || e.keyCode == 40)
{
}
else
{
e.preventDefault(); // stops the keypress occuring
alert('No more profile tags are allowed');
}
}
});

Set an event handler (onkeyup) on input box so that whenever user hits a key the handler gets called
In event handler take the values of input box and split them on comma
Check if any value is duplicate
If no return true
If yes show an alert
Synopsis:
$(".myprofiletags").keydown (function (e) {
alert ($(this).val());
});
You can also use change
$('input[name^="text"]').change(function() {
Edit: You are going in right direction, just split the value on comma and use each splitted value as an item of array.
See how to do that:
Split comma-separated input box values into array in jquery, and loop through it
Convert comma separated string to array

How to prevent user from entering decimals?

I've got an order page on my site. Some order items can have decimal quantities, some can't.
What's the best way to prevent the user from entering decimal quantities? (Apart from an alert box and setting the field to zero)?

Intercept key events for the field, detect illegal characters upon input, keep them from getting entered in the field and add a temporary msg near the field (inserted into the page) that explains what characters or values are allowed. pop up alerts are a bad way to give feedback in the middle of typing.
Then, validate again before submission because there are other ways to get data into fields (drag/drop, copy/paste, etc...) that you might not have caught everything.
Here's a jQuery example of both an integer only and a decimal only field with temporary messages displayed when invalid keys are typed:
Working jsFiddle: http://jsfiddle.net/jfriend00/CkDTy/
$(".integer").keypress(function(e) {
if (e.which < 48 || e.which > 57) {
showAdvice(this, "Integer values only");
return(false);
}
});
$(".decimal").keypress(function(e) {
// 46 is a period
if (e.which != 46 && (e.which < 48 || e.which > 57)) {
showAdvice(this, "Decimal numbers only");
return(false);
}
if (e.which == 46 && this.value.indexOf(".") != -1) {
showAdvice(this, "Only one period allowed in decimal numbers");
return(false); // only one decimal allowed
}
});
function showAdvice(obj, msg) {
$("#singleAdvice").stop(true, false).remove();
$('<span id="singleAdvice" class="advice">' + msg + '</span>').insertAfter(obj);
$("#singleAdvice").delay(4000).fadeOut(1500);
}

Here's a little jQuery that prevents non-numerical inputs:
$(function() {
$('input').bind('keyup', function(event) {
var currValue = $(this).val();
if(currValue.search(/[^0-9]/) != -1)
{
// Change this to something less obnoxious
alert('Only numerical inputs please');
}
$(this).val(currValue.replace(/[^0-9]/, ''));
});
});

You can add an event (on key press) and detect if a decimal point has been pressed by the user or not. Also on form submission, use regular expressions to check if the submitted data is correct (because the user can forge the data using live editor like firebug). Also make sure to double check that on your server side in case if user disabled javascript.
for example:
<input type="text" onkeypress="checkDecimal();" />
<input type="submit" onclick="checkBeforeSubmit();" />
function checkDecimal() {
// your code goes here
}
function checkBeforeSubmit() {
// your code goes here
}
You better to use the same function cause it's basically the same thing and invoke it from both events.
On server side, check the submitted data again

How to ignore unwanted characters from textbox (JavaScript or jQuery)

There's a TextBox that I wanna allow users to just enter numbers & not any alphabetical characters.
So how could I ignore those chars entered by end user via JavaScript or jQuery?
Notice I don't wanna replace user's entered value by empty string; Instead wanna ignore case if there is any way for it.

Try that code:
$("#id").keypress(function (e) {
//if the letter is not digit then display error and don't type anything
if ( e.which!=8 && e.which!=0 && (e.which<48 || e.which>57)) {
return false;
}
});
reference http://roshanbh.com.np/2008/04/textbox-accept-only-numbers-digits.html

You want to attach a handler to the textbox's keypress event. In here check the event.which property to find out what key is pressed, and if it's not a number (between keycodes 48 and 57) return false, which will cancel the default behaviour of typing in the textbox.
$("input").keypress(function (e) {
if (e.which < 48 || e.which > 57)
return false;
});

I would not recommend intercepting keystrokes, allow the user to type whatever he/she wants, and validate on user action (submit/select etc).
Look at this jQuery plugin for instance: http://bassistance.de/jquery-plugins/jquery-plugin-validation/

you said you didn't want to include alphabetical then you said you just want to ignore case? what do you need to do?
You can ignore lower case in JS by using string.toLowerCase()

For numeric-only I use this jQuery extension/plug in
http://www.texotela.co.uk/code/jquery/numeric/

In above options we can prevent the user from keyboard, but what if the user paste something, it will not restrict user to not paste any special character.
For example we are restricting it from keyboard with proper error msg
<script type="text/javascript">
$(function () {
$("#package").keypress(function (e) {
var keyCode = e.keyCode || e.which;
$("#lblError").html("");
//Regex for Valid Characters i.e. Alphabets and Numbers.
var regex = /^[A-Za-z0-9]+$/;
//Validate TextBox value against the Regex.
var isValid = regex.test(String.fromCharCode(keyCode));
if (!isValid) {
$("#lblError").html("Only Alphabets and Numbers allowed.");
}
else
{
$("#lblError").html("");
}
return isValid;
});
});
</script>
Now let's prevent it from pasting special character.
$('#package').bind("paste",function(){
var data= $('#package').val() ;
var removedNotAllowed = data.replace(/[^ws]/gi, '');
$( '#package' ).val(removedNotAllowed);
$("#lblError").html("Only Alphabets and Numbers allowed.");
});

Best way to restrict a text field to numbers only?

I'm using the following Javascript to restrict a text field on my website to only accept numerical input, and no other letters or characters. The problem is, it REALLY rejects all other key inputs, like ctrl-A to select the text, or even any other browser functions like ctrl-T or ctrl-W while the text box is selected. Does anyone know of a better script to only allow numerical input, but not block normal commands (that aren't being directly input into the field)? Thanks
Here is the code I'm using now:
function numbersonly(e, decimal)
{
var key;
var keychar;
if (window.event)
key = window.event.keyCode;
else if (e)
key = e.which;
else
return true;
keychar = String.fromCharCode(key);
if ((key==null) || (key==0) || (key==8) || (key==9) || (key==13) || (key==27))
return true;
else if ((("0123456789").indexOf(keychar) > -1))
return true;
else if (decimal && (keychar == "."))
return true;
else
return false;
}
Edit: None of the solutions provided have solved my problem of allowing commands like ctrl-A while the text box is selected. That was the whole point of my asking here, so I have gone back to using my original script. Oh well.

This is something I made another time for just numbers, it will allow all the formatters as well.
jQuery
$('input').keypress(function(e) {
var a = [];
var k = e.which;
for (i = 48; i < 58; i++)
a.push(i);
if (!(a.indexOf(k)>=0))
e.preventDefault();
});​
Try it
http://jsfiddle.net/zpg8k/
As a note, you'll want to filter on submit/server side as well, for sake of pasting/context menu and browsers that don't support the paste event.
Edit to elaborate on multiple methods
I see you're bouncing around the 'accepted' answer, so I'll clear something up. You can really use any of the methods listed here, they all work. What I'd personally do is use mine for live client side filtering, and then on submit and server side use RegEx as suggested by others. However, no client side by itself will be 100% effective as there is nothing stopping me from putting document.getElementById('theInput').value = 'Hey, letters.';
in the console and bypassing any clientside verification (except for polling, but I could just cancel the setInterval from the console as well). Use whichever client side solution you like, but be sure you implement something on submit and server side as well.
Edit 2 - #Tim Down
Alright, per the comments I had to adjust two things I didn't think of. First, keypress instead of keydown, which has been updated, but the lack of indexOf in IE (seriously Microsoft!?) breaks the example above as well. Here's an alternative
$('input').keypress(function(e) {
var a = [];
var k = e.which;
for (i = 48; i < 58; i++)
a.push(i);
if (!($.inArray(k,a)>=0))
e.preventDefault();
});​
New jsfiddle: http://jsfiddle.net/umNuB/

This works in IE, Chrome AND Firefox:
<input type="text" onkeypress="return event.charCode === 0 || /\d/.test(String.fromCharCode(event.charCode));" />

.keypress(function(e)
{
var key_codes = [48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 0, 8];
if (!($.inArray(e.which, key_codes) >= 0)) {
e.preventDefault();
}
});
You need Backspace and Delete keys too ;)

http://jsfiddle.net/PgHFp/
<html>
<head>
<title>Test</title>
<script language="javascript">
function checkInput(ob) {
var invalidChars = /[^0-9]/gi
if(invalidChars.test(ob.value)) {
ob.value = ob.value.replace(invalidChars,"");
}
}
</script>
</head>
<body>
<input type="text" onkeyup="checkInput(this)"/>
</body>
</html>

Just use regex to get rid of any non number characters whenever a key is pressed or the textbox loses focus.
var numInput;
window.onload = function () {
numInput = document.getElementById('numonly');
numInput.onkeydown = numInput.onblur = numInput.onkeyup = function()
{
numInput.value = numInput.value.replace(/[^0-9]+/,"");
}
}

The only event that contains information about the character typed is keypress. Anything character-related you may infer from the keyCode property of keydown or keyup events is unreliable and dependent on a particular keyboard mapping. The following will prevent non-numeric keyboard input all major browsers by using the character obtained from the keypress event. It won't prevent the user from pasting or dragging non-numeric text in.
var input = document.getElementById("your_input");
input.onkeypress = function(evt) {
evt = evt || window.event;
if (!evt.ctrlKey && !evt.metaKey && !evt.altKey) {
var charCode = (typeof evt.which == "undefined") ? evt.keyCode : evt.which;
if (charCode && !/\d/.test(String.fromCharCode(charCode))) {
return false;
}
}
};

I use this:
oEl.keypress(function(ev)
{
var sKey = String.fromCharCode(ev.which);
if (!sKey.match(/[0-9]/) || !sKey === "")
ev.preventDefault();
});
The advantage is, that every key which does not provide an input to the field is still allowed, so you don't have to worry about every single special key. Even combos like CTRL + R do still work.
EDIT
As this is not working in Firefox I had to modify the function a little:
oEl.keypress(function(ev)
{
var iKeyCode = ev.which || ev.keyCode;
var aSpecialKeysForFirefox = [8, 9, 13, 27, 37, 38, 39, 40, 46];
var sKey = String.fromCharCode(iKeyCode);
if (sKey !== "" && $.inArray(iKeyCode, aSpecialKeysForFirefox ) < 0 && !sKey.match(/[0-9]/)) {
ev.preventDefault();
}
});
Explanation
All Browsers handle jquerys keypress event differently. To make it work in FF the $.inArray check is added. As firefoxs keypress-event doesn't trigger when combinations like strg+tab are used, but the others do, the key.match approach still adds a little value to the latter, as it enables those combinations.

Maybe you are using bootstrap. If so, this may suffice:
<input type="text" data-mask="9999999">
Input mask

The following code is something I use extensively. I found the script in a forum, but modified and expanded it to accommodate my needs:
<script type="text/javascript">
// Restrict user input in a text field
// create as many regular expressions here as you need:
var digitsOnly = /[1234567890]/g;
var integerOnly = /[0-9\.]/g;
var alphaOnly = /[A-Za-z]/g;
var usernameOnly = /[0-9A-Za-z\._-]/g;
function restrictInput(myfield, e, restrictionType, checkdot){
if (!e) var e = window.event
if (e.keyCode) code = e.keyCode;
else if (e.which) code = e.which;
var character = String.fromCharCode(code);
// if user pressed esc... remove focus from field...
if (code==27) { this.blur(); return false; }
// ignore if the user presses other keys
// strange because code: 39 is the down key AND ' key...
// and DEL also equals .
if (!e.ctrlKey && code!=9 && code!=8 && code!=36 && code!=37 && code!=38 && (code!=39 || (code==39 && character=="'")) && code!=40) {
if (character.match(restrictionType)) {
if(checkdot == "checkdot"){
return !isNaN(myfield.value.toString() + character);
} else {
return true;
}
} else {
return false;
}
}
}
</script>
Different usage methods would be:
<!-- To accept only alphabets -->
<input type="text" onkeypress="return restrictInput(this, event, alphaOnly);">
<!-- To accept only numbers without dot -->
<input type="text" onkeypress="return restrictInput(this, event, digitsOnly);">
<!-- To accept only numbers and dot -->
<input type="text" onkeypress="return restrictInput(this, event, integerOnly);">
<!-- To accept only numbers and only one dot -->
<input type="text" onkeypress="return restrictInput(this, event, integerOnly, 'checkdot');">
<!-- To accept only characters for a username field -->
<input type="text" onkeypress="return restrictInput(this, event, usernameOnly);">

Add <script type="text/javascript" src="jquery.numeric.js"></script> then use
$("element").numeric({ decimal: false, negative: false });

shorter way and easy to understand:
$('#someID').keypress(function(e) {
var k = e.which;
if (k <= 48 || k >= 58) {e.preventDefault()};
});

This is a variation on Robert's answer that allows a single decimal point to be entered. If a decimal point has already been entered, only numbers are accepted as input.
JSFiddle - decimal number input
// Allow only decimal number input
$('#decimalInput').keypress(function (e) {
var a = [];
var k = e.which;
for (i = 48; i < 58; i++)
a.push(i);
// allow a max of 1 decimal point to be entered
if (this.value.indexOf(".") === -1) {
a.push(46);
}
if (!(a.indexOf(k) >= 0)) e.preventDefault();
$('span').text('KeyCode: ' + k);
});

I know that there are already many answers but for the sake of simplicity i would like to add another answer which is simple and self explanatory in which we do not have to remember keycodes and it also works across all browsers.
document.getElementById('myinput').onkeydown = function(e)
{
console.log(e.key);
//console.log(e.target.value);
switch (e.key)
{
case "1":
case "2":
case "3":
case "4":
case "5":
case "6":
case "7":
case "8":
case "9":
case "0":
case "Backspace":
return true;
break;
case ".":
if (e.target.value.indexOf(".") == -1)
{
return true;
}
else
{
return false;
}
break;
default:
return false;
}
}
<input type="text" placeholder="Enter Value" id="myinput" />

It's worth pointing out that no matter how tightly you manage to control this via the front end (Javascript, HTML, etc), you still need to validate it at the server, because there's nothing to stop a user from turning off javascript, or even deliberately posting junk to your form to try to hack you.
My advice: Use the HTML5 markup so that browsers which support it will use it. Also use the JQuery option previously suggested (the inital solution may have flaws, but it seems like the comments have been working through that). And then do server-side validation as well.

this will enable the numpad inputs also.
.keydown(function(event){
if(event.keyCode == 8 || event.keyCode == 46)
return true;
if(event.keyCode >= 96 && event.keyCode <= 105)
return true;
if(isNaN(parseInt(String.fromCharCode(event.keyCode),10)))
return false;
});

In order to block anything but numbers from being input into a text field but still allowing for other buttons to work (such as delete, shift, tab, etc.) look at a reference of the Javascript key codes; anything from 65 on up (to 222) can be blocked.
Using Jquery and Javascript, that would look like:
$('#textFieldId').keydown(function(event) {
if ( event.keyCode > 64 ) {
event.preventDefault();
}
});
The key codes will be the same in Javascript whether or not Jquery is used.

Here is my solution: a combination of the working ones below.
var checkInput = function(e) {
if (!e) {
e = window.event;
}
var code = e.keyCode || e.which;
if (!e.ctrlKey) {
//46, 8, 9, 27, 13 = backspace, delete, tab, escape, and enter
if (code == 8 || code == 13 || code == 9 || code == 27 || code == 46)
return true;
//35..39 - home, end, left, right
if (code >= 35 && code <= 39)
return true;
//numpad numbers
if (code >= 96 && code <= 105)
return true;
//keyboard numbers
if (isNaN(parseInt(String.fromCharCode(code), 10))) {
e.preventDefault();
return false;
}
}
return true;
};

I came across your question while trying to figure this out myself. Here is the solution that I came up with.
// Prevent user from entering non-numeric characters in number boxes.
(function (inputs) {
var input;
var f = function (e) {
var unicodeRe = /U\+(\d+)/;
// Chrome doesn't support the standard key property, so use keyIdentifier instead.
// Instead of the actual character that "key" returns, keyIdentifier returns
// A string such as "U+004F" representing the unicode character.
// For special characters (e.g., "Shift", a string containing the name of the key is returned.)
var ch = e.key || e.keyIdentifier;
var match = ch.match(unicodeRe);
// keyIdentifier returns a unicode. Convert to string.
if (match) {
ch = String.fromCharCode(Number.parseInt(match[1], 16));
}
console.log(ch);
if (ch.length === 1 && /[^0-9]/.test(ch)) {
if (!/[\b]/.test(ch)) { // Don't prevent backspace.
e.preventDefault();
}
}
};
for (var i = 0, l = inputs.length; i < l; i += 1) {
input = inputs[i];
input.onkeydown = f;
}
}(document.querySelectorAll("input[type=number],#routeFilterBox")));
Edit: I've discovered that my solution does not allow the user to enter numbers via the numpad in Chrome. The 0-9 keypad keys seem to be returning the character "`" for 0 and A-I for the rest of the number keys.

All of the answers are outdated, lengthy and will cause annoyance to your users. Most of them don’t even filter or allow pasted content.
Instead of filtering the input, do some validation before submitting the form and then also server-side.
HTML has validation included:
<input type="number" pattern="[0-9]+">
This also enables the number keyboard on mobile.

This is my plugin for that case:
(function( $ ) {
$.fn.numbers = function(options) {
$(this).keypress(function(evt){
var setting = $.extend( {
'digits' : 8
}, options);
if($(this).val().length > (setting.digits - 1) && evt.which != 8){
evt.preventDefault();
}
else{
if(evt.which < 48 || evt.which > 57){
if(evt.keyCode != 8){
evt.preventDefault();
}
}
}
});
};
})( jQuery );
Use:
$('#limin').numbers({digits:3});
$('#limax').numbers();

There is my current solution of numeric input, need to test in different browsers but seems to work
Support comma and period delimiter (czech native is comma), space and numpad/keyboard numbers input. Allow Ctrl+C Ctrl+A or Ctrl+X, arrow navigation and delete block Ctrl+V. React on escape key by blurring input.
Watch my Coffee script:
(($) ->
$.fn.onlyNumbers = ->
#each ->
$(#).keydown (e) ->
# get code of key
code = if e.keyCode then e.keyCode else e.which
return $(#).blur() if code is 27 # blur on escape
return if code in [46, 8, 9, 13] # 46, 8, 9, 27, 13 = backspace, delete, tab, escape, and enter
return if (e.ctrlKey or e.metaKey) and code in [65, 67, 88] # ctrl|command + [a, c, x]
return if code in [96..105] # numpad numbers
return if code in [48..57] # numbers on keyboard
return if code in [35..39] # 35..39 - home, end, left, right
return if code in [188, 190, 32] # comma, period, space
return if code in [44] # comma, period,
e.returnValue = false # IE hate you
e.preventDefault();
$(#).keypress (e) ->
code = if e.keyCode then e.keyCode else e.which
return if code in [44, 46, 32] # comma, period, space
return if code in [48..57] # numbers on keyboard
e.returnValue = false # IE hate you
e.preventDefault();
) jQuery
You can get compiled Javascript here http://goo.gl/SbyhXN

My functions:
$('.input_integer_only').on('input', function(e) {
$(this).val($(this).val().replace(/[^0-9]/g, ''));
});
$('.input_float_only').on('input', function(e) {
var $var = $(this).val().replace(/[^0-9\.]/g, '');
var $aVar = $var.split('.');
if($aVar.length > 2) {
$var = $aVar[0] + '.' + $aVar[1];
}
$(this).val($var);
});

You can make changes to accept the keycode for Ctrl keys: 17, 18, 19, 20.
Then your code will be like:
function numbersonly(e, decimal) {
var key;
var keychar;
if (window.event)
key = window.event.keyCode;
else if (e)
key = e.which;
else
return true;
keychar = String.fromCharCode(key);
if ((key==null) || (key==0) || (key==8) || (key==9) || (key==13) || (key==27) || (key==17) || (key==18) || (key==19) || (key==20))
return true;
else if ((("0123456789").indexOf(keychar) > -1))
return true;
else if (decimal && (keychar == "."))
return true;
else
return false;
}

document.getElementById('myinput').onkeydown = function(e) {
if(!((e.keyCode > 95 && e.keyCode < 106)
|| (e.keyCode > 47 && e.keyCode < 58)
|| e.keyCode == 8
|| e.keyCode == 9)) {
return false;
}
}

You can do like this to accept only Numbers in text Box,
function onChange(event){
var ckeckChars = /[^0-9]/gi;
if(checkChars.test(event.target.value)) {
event.target.value = event.target.value.replace(ckeckChars,"");
}

I am using below in Angular to restrict character
in HTML
For Number Only
<input
type="text"
id="score"
(keypress) ="onInputChange($event,'[0-9]')"
maxlength="3"
class="form-control">
for Alphabets Only
<input
type="text"
id="state"
(keypress) ="onInputChange($event,'[a-zA-Z]')"
maxlength="3"
class="form-control">
In TypeScript
onInputChange(event: any, inpPattern:string): void {
var input = event.key;
if(input.match(inpPattern)==null){
event.preventDefault();
}
}

This JavaScript function will be used to restrict alphabets and
special characters in Textbox , only numbers, delete, arrow keys and
backspace will be allowed. JavaScript Code Snippet - Allow Numbers
in TextBox, Restrict Alphabets and Special Characters
Tested in IE & Chrome.
JavaScript function
<script type="text/javascript">
/*code: 48-57 Numbers
8 - Backspace,
35 - home key, 36 - End key
37-40: Arrow keys, 46 - Delete key*/
function restrictAlphabets(e){
var flag = false;
var x = e.which || e.keycode;
if ((x >= 48 && x <= 57) || x == 8 ||
(x >= 35 && x <= 40) || x == 46)
flag = true;
else
flag = false;
if (flag && e.keyCode === 46 && $(e.currentTarget).val().split('.').length === 2) {
flag = false;
}
return flag;
}
</script>
HTML Source Code with JavaScript
<html>
<head>
<title>JavaScript - Allow only numbers in TextBox (Restrict Alphabets and Special Characters).</title>
<script type="text/javascript">
/*code: 48-57 Numbers
8 - Backspace,
35 - home key, 36 - End key
37-40: Arrow keys, 46 - Delete key*/
function restrictAlphabets(e){
var x=e.which||e.keycode;
if((x>=48 && x<=57) || x==8 ||
(x>=35 && x<=40)|| x==46)
return true;
else
return false;
}
</script>
</head>
<body style="text-align: center;">
<h1>JavaScript - Allow only numbers in TextBox (Restrict Alphabets and Special Characters).</h1>
<big>Enter numbers only: </big>
<input type="text" onkeypress='return restrictAlphabets(event)'/>
</body>
</html>
Refrence

You can handle te event on html by introducing keypresshandler function
function keypresshandler(event)
{
var charCode = event.keyCode;
//You condition
if (charCode == 58 ){
event.preventDefault();
return false;
}
}

Javascript is often used on the browser client side to perform simple tasks that would otherwise require a full postback to the server. Many of those simple tasks involve processing text or characters entered into a form element on a web page, and it is often necessary to know the javascript keycode associated with a character. Here is a reference.
Press a key in the text box below to see the corresponding Javascript key code.
function restrictCharacters(evt) {
evt = (evt) ? evt : window.event;
var charCode = (evt.which) ? evt.which : evt.keyCode;
if (((charCode >= '48') && (charCode <= '57')) || (charCode == '44')) {
return true;
}
else {
return false;
}
}
Enter Text:
<input type="text" id="number" onkeypress="return restrictCharacters(event);" />