Develop Reference

How to allow only numbers in textbox

function AllowOnlyNumbers(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57)){
if (charCode === 8 && charCode === 46) {
return false;
}
}
return true;
}
How to allow only numbers and delete key or backspace to be written in this textbox ?

Why not use input of type number <input type="number" /> for browsers that supports it, otherwise use javascript:
function AllowOnlyNumbers(evt) {
evt = (evt) ? evt : window.event;
var charCode = (evt.which) ? evt.which : evt.keyCode;
if (charCode > 31 && (charCode < 48 || charCode > 57)) {
return false;
}
return true;
}
Here is a fiddle: http://jsfiddle.net/Lm2hS/
From: https://stackoverflow.com/a/7295864/235659

I have created this solution for your problem here:
https://codebrace.com/editor/b05f92054
Here I have used event.charCode == 0 to allow non characters key pressed (To allow delete, backspace and other non-character keys) and isNaN to check if the value entered is a number or not.
I hope this helps!

Why my code doesn't allow specific symbols?

I am using this code to allow only digits to type in textbox but now I want to allow . too. I modified this code but not working.
function isNumberKeyDotAllowed(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57) && charCode == 46)
return false;
return true;
}
TextBox declaration in markup:
<asp:TextBox runat="server" ID="txtBoxApplicantCNICNo"
onkeypress="return isNumberKeyDotAllowed(this)" AutoPostBack=True
OnTextChanged="txtCHan_event" CssClass="form-control">

I see two problems with your code. The first is that you pass this as the argument to isNumberKeyDotAllowed while you should pass event:
onkeypress="return isNumberKeyDotAllowed(event);"
The second is the validation condition. Here is my own version of the function. I defined the condition for success instead of the condition for failure, because it is easier for me to figure out:
function isNumberKeyDotAllowed(evt) {
var charCode = evt.which ? evt.which : evt.keyCode;
if (charCode == 46 || (48 <= charCode && charCode <= 57)) {
return true;
}
else {
return false;
}
}

Javascript validation won't allow periods/decimal points

I'm having some trouble adding validation for stops to my input box. The restriction on allowing numbers only (second condition) works, but the first condition may as well not exist. Full stops and decimal points still do not appear in the input box.
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode == 110 || charCode == 190)
return true;
else if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
Additionally, I've noticed that the behaviour of this JS is different across browsers. in FireFox, I can use the numeric keypad to enter a value. However, in Chrome I am limited to the top row of numbers. Neither browser allows decimal points.

onkeypress won't report the key codes, it will report the ASCII character typed. You want onkeydown
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode == 110 || charCode == 190)
return true;
else if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
document.getElementById('foo').onkeydown = isNumberKey;
<input type="text" id="foo" />

text field that only allow and number and dash and also accepts ctrl commands

function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode != 45 && charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
i have been using this function but its does not allow ctrl + commands.
like ctrl + a , ctrl + c

May be you want to do something like this to sort it out:
function isNumberKey(evt) {
var charCode = evt.which || event.keyCode;
if (!evt.ctrlKey && charCode != 45 && charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
just check if ctrlKey is pressed, if do then only in conjunction with !evt.ctrlKey disable it.

asp textbox javascript validator

there are many post about how to prevent an ASP textbox to accept only numbers, but could somebody give me a JS example, how to check if the entered value is between 0-100?
My validator fires each time key is entered and checks if it is a number or not, but do not know how to extend it to check the final value against 0-100 range.
function onlyDotsAndNumbers(event) {
var charCode = (event.which) ? event.which : event.keyCode
if (charCode == 46) {
return true;
}
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
Cheers
A

You need to check out the whole value of the text box.
function onlyDotsAndNumbers(event) {
var charCode = (event.which) ? event.which : event.keyCode
if (charCode == 46) {
return true;
}
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
var boxValue = $(event.target).val();
if (boxValue > 100 || boxValue < 0)
return false;
return true;
}