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!

How to prevent non numeric Character and accepts 3 decimal places

I have this code it's working but it's accept small letter (e) and big (E)
How can I prevent that? I've seen some similar codes that also accepts (e & E)
function isNumberKeyDecimal(evt)
{
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57) && charCode != 46)
return false;
return true;
}

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" />

How can i set more than one id in one function

i have 2 function in jquery like this :-
$('#age').on('keypress', function(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
return !(charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57));
});
$('#phone').on('keypress', function(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
return !(charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57));
});
this tow function is same to do .
so i need to mearge this tow function in one like :-
$('#phone') + $('#age').on('keypress', function(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
return !(charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57));
});

like this: just for demo sake: http://jsfiddle.net/2ASnz/
You can combine multiple selectors with a comma.
This link will give you more insight: http://api.jquery.com/multiple-selector/
Hope this help :)
code
$('#phone,#age').on('keypress', function(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
return !(charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57));
});
http://api.jquery.com/multiple-selector/
You can specify any number of selectors to combine into a single
result. This multiple expression combinator is an efficient way to
select disparate elements. The order of the DOM elements in the
returned jQuery object may not be identical, as they will be in
document order. An alternative to this combinator is the .add()
method.

try this
$('#phone,#age').on('keypress', function(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
return !(charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57));
});

Give the two elements same class and select them by their class, then do same thing to both elements.

jQuery generally works on collections. You can pass more than one selector expression separated by commas. This will work as you required.
$('#phone, #age').on('keypress', function(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
return !(charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57));
});

You can just use , in your selectors to have multiple selectors Multiple Selectors
$('#phone,#age').on('keypress', function(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode;
return !(charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57));
});