How to make HTML input tag only accept numerical values?

You can also use the pattern attribute in html5:

<input type="text" name="name" pattern="[0-9]" title="Title" /> 

Input validation tutorial

Although, if your doctype isn't html then I think you'll need to use some javascript/jquery.

Quick and Easy Code

<input type="text" onkeypress="return (event.charCode !=8 && event.charCode ==0 || (event.charCode >= 48 && event.charCode <= 57))" />

This will permit usage of numbers and backspace only.

If you need decimal part too, use this code fragment

<input type="text" onkeypress="return (event.charCode !=8 && event.charCode ==0 || ( event.charCode == 46 || (event.charCode >= 48 && event.charCode <= 57)))" />

You can use following one line code as :

<input type="text" onkeypress="return /[0-9]/i.test(event.key)" >

It will accept numbers ony.

<input type="text" onkeypress="return /[0-9]/i.test(event.key)" placeholder="Can accept numbers only" >

Please try this code along with the input field itself

<input type="text" name="price" id="price_per_ticket" class="calculator-input" onkeypress="return event.charCode >= 48 && event.charCode <= 57"></div>

it will work fine.

You can use an <input type="number" />. This will only allow numbers to be entered into othe input box.

Example: http://jsfiddle.net/SPqY3/

Please note that the input type="number" tag is only supported in newer browsers.

For firefox, you can validate the input by using javascript:

http://jsfiddle.net/VmtF5/

Update 2018-03-12: Browser support is much better now it's supported by the following:

• Chrome 6+
• Firefox 29+
• Opera 10.1+
• Safari 5+
• Edge
• (Internet Explorer 10+)

You can use the <input> tag with attribute type='number'

For example you can use <input type='number' />

This input field allows only numerical values. You can also specify the minimum value and maximum value that should be accepted by this field.

I have used a regular expression to replace the input value with the pattern needed.

function restrictNumber(e) {
  var newValue = this.value.replace(new RegExp(/[^\d]/, 'ig'), "");
  this.value = newValue;
}

var userName = document.querySelector('#numberField');
userName.addEventListener('input', restrictNumber);

<input type="text" id="numberField">

<input type="text" name="myinput" id="myinput" onkeypress="return isNumber(event);" />

and in JS:

function isNumber(e){
    e = e || window.event;
    var charCode = e.which ? e.which : e.keyCode;
    return /\d/.test(String.fromCharCode(charCode));
}

or you can write it in a complicated but useful way:

<input onkeypress="return /\d/.test(String.fromCharCode(((event||window.event).which||(event||window.event).which)));" type="text" name="myinput" id="myinput" />

Note: cross-browser and regex in literal.

<input type="phone" onkeyup="value=value.replace(/[^\d]/g,'')" name="personalPhone" lay-verify="personalPhone" autocomplete="off" placeholder="Input Your Telephone Number" class="layui-input">

Add inside your input tag: onkeyup="value=value.replace(/[^\d]/g,'')"

Simple enough?

inputField.addEventListener('input', function () {
  if ((inputField.value/inputField.value) !== 1) {
    console.log("Please enter a number");
  }
});

<input id="inputField" type="text">

<input 
    onkeyup="value=isNaN(parseFloat(value))?1000:value" 
    type="number" 
    value="1000"
>

onkeyup triggers when the key is released.

isNaN(parseFloat(value))? checks if the input value is not a number.

If it is not a number the value is set to 1000 : If it is a number the value is set to the value.

Note: For some reason it only works with type="number"

To make it even more exciting, you can also have a boundary:

<input 
    onkeyup="value=isNaN(parseFloat(value))||value<0||value>9000?1000:value"
    type="number"
    value="1000"
>

I fought with this one for a bit. Many solutions here and elsewhere seemed complicated. This solution uses jQuery/javascript alongside HTML.

$(document).on('change', '.validateNumber', function() {
  var abc = parseInt($(this).val());
  if (isNaN(abc)) abc = 1;
  $(this).val(abc);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="number" min="1" class="validateNumber">

In my case I was tracking small quantities with a minimum value of 1, hence the min="1" in the input tag and abc = 1 in the isNaN() check. For positive-only numbers you could change those values to 0 and even simply remove the min="1" from the input tag to allow for negative numbers.

Also this works for multiple boxes (and could save you some load time over doing them individually by id), just add the "validateNumber" class where needed.

Explanation

parseInt() basically does what you need, except that it returns NaN rather than some integer value. With a simple if(), you can set the "fallback" value that you prefer in all the cases NaN is returned.

Also, W3 Schools states here that the global version of NaN will type cast before checking which gives some extra proofing (Number.isNaN() does not do that). Any values sent to a server/backend should still be validated there!

I use this for zip codes, quick and easy.

<input type="text" id="zip_code" name="zip_code" onkeypress="return event.charCode > 47 && event.charCode < 58;" pattern="[0-9]{5}" required></input>

How about using <input type="number"...>?

http://www.w3schools.com/tags/tag_input.asp

Also, here is a question that has some examples of using Javascript for validation.

Update: linked to better question (thanks alexblum).

The accepted answer:

function isNumberKey(evt){
    var charCode = (evt.which) ? evt.which : event.keyCode
    if (charCode > 31 && (charCode < 48 || charCode > 57))
        return false;
    return true;
}

It's good but not perfect. It works out for me, but I get a warning that the if-statement can be simplified.

Then it looks like this, which is way prettier:

function isNumberKey(evt){
    var charCode = (evt.which) ? evt.which : event.keyCode;
    return !(charCode > 31 && (charCode < 48 || charCode > 57));
}

I updated some answers posted to add the following:

• Add the method as extension method
• Allow only one point to be entered
• Specify how many numbers after the decimal point is allowed.

String.prototype.isDecimal = function isDecimal(evt,decimalPts) {
    debugger;
    var charCode = (evt.which) ? evt.which : event.keyCode
    if (charCode > 31 && (charCode != 46 && (charCode < 48 || charCode > 57)))
        return false;
  
    //Prevent more than one point
    if (charCode == 46 && this.includes("."))
        return false;

    // Restrict the needed decimal digits
    if (this.includes("."))
    {
        var number = [];
        number = this.split(".");
        if (number[1].length == decimalPts)
             return false;
     }

     return true;
};

Please see my project of the cross-browser filter of value of the text input element on your web page using JavaScript language: Input Key Filter . You can filter the value as an integer number, a float number, or write a custom filter, such as a phone number filter. See an example of code of input an integer number:

<!doctype html>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>Input Key Filter Test</title>
	<meta name="author" content="Andrej Hristoliubov [email protected]">
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
	
	<!-- For compatibility of IE browser with audio element in the beep() function.
	https://www.modern.ie/en-us/performance/how-to-use-x-ua-compatible -->
	<meta http-equiv="X-UA-Compatible" content="IE=9"/>
	
	<link rel="stylesheet" href="https://rawgit.com/anhr/InputKeyFilter/master/InputKeyFilter.css" type="text/css">		
	<script type="text/javascript" src="https://rawgit.com/anhr/InputKeyFilter/master/Common.js"></script>
	<script type="text/javascript" src="https://rawgit.com/anhr/InputKeyFilter/master/InputKeyFilter.js"></script>
	
</head>
<body>
	<h1>Integer field</h1>
<input id="Integer">
<script>
	CreateIntFilter("Integer", function(event){//onChange event
			inputKeyFilter.RemoveMyTooltip();
			var elementNewInteger = document.getElementById("NewInteger");
			var integer = parseInt(this.value);
			if(inputKeyFilter.isNaN(integer, this)){
				elementNewInteger.innerHTML = "";
				return;
			}
			//elementNewInteger.innerText = integer;//Uncompatible with FireFox
			elementNewInteger.innerHTML = integer;
		}
		
		//onblur event. Use this function if you want set focus to the input element again if input value is NaN. (empty or invalid)
		, function(event){ inputKeyFilter.isNaN(parseInt(this.value), this); }
	);
</script>
 New integer: <span id="NewInteger"></span>
</body>
</html>

Also see my page "Integer field:" of the example of the input key filter

Yet another method that works pretty well.

<input type="text" name="celular" placeholder="Ej. 6756892" maxlength="8" id="telefono"   oninput="this.value = this.value.replace(/[^0-9.]/g, '').replace(/(\..*)\./g, '$1');" >

What's great about this fix is that copy-pasted values are also included in the rule.

I found that this works. It improves the user experience by showing a numeric keyboard and throws an error when the entered value isn't a number.

const numInput = document.querySelector("input[type='text']");

numInput.addEventListener("input", () => {
  if (!/^\d+$/.test(numInput.value)) {
    alert("Input must be a number!");
  }
});

<input type="text" inputmode="numeric" pattern="[0-9]+">

The JS will display an alert if the input isn't a number.

If you can use HTML5 you can do <input type="number" />

If not you will have to either do it through javascript as you said it doesn't get submitted to do it from code behind.

function validate() {
  var returnString;
  var text = document.getElementById('numbersOnly').value;
  var regex = /[0-9]|\./;
  var anArray = text.split('');
  for (var i = 0; i < anArray.length; i++) {
    if (!regex.test(anArray[i])) {
      anArray[i] = '';
    }
  }
  for (var i = 0; i < anArray.length; i++) {
    returnString += anArray[i];
  }
  document.getElementById('numbersOnly').value = returnString;
}

<input id="numbersOnly" onkeypress='validate()' />

P.S: I didn't test the code but it should be more or less correct if not check for typos. You might wanna add a few more things like what to do if the string is null or empty etc. Also, you could make this quicker.

If not integer set 0

$('#min-value').change(function() {
  var checkvalue = $('#min-value').val();
  if (checkvalue != parseInt(checkvalue))
    $('#min-value').val(0);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="text" id="min-value" />

you can use this too

<input onkeypress="return /\d/i.test(event.key)" />

When using this code you cant use "BackSpace Button" in Mozilla Firefox you can only use backspace in Chrome 47 && event.charCode < 58;" pattern="[0-9]{5}" required>

http://www.texotela.co.uk/code/jquery/numeric/ numeric input credits to Leo Vũ for mentioning this and of course TexoTela. with a test page.

For general purpose, you can have JS validation as below:

It will work for Numeric keypad and normal number key's

function isNumberKey(evt){
        var charCode = (evt.which) ? evt.which : event.keyCode

if (charCode < 31 || (charCode >= 48 && charCode <= 57 ) || (charCode >= 96 && charCode <= 105 ))
        return true;
    return false;
}

<input name="someid" type="number" onkeypress="return isNumberKey(event)"/>

One way could be to have an array of allowed character codes and then use the Array.includes function to see if entered character is allowed.

Example:

<input type="text" onkeypress="return [45, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57].includes(event.charCode);"/>

You can use it by one line

<input onkeypress="return /[0-9]/i.test(event.key)" >

It's better to add "+" to REGEX condition in order to accept multiple digits (not only one digit):

<input type="text" name="your_field" pattern="[0-9]+">