I need to make sure that a certain <input> field only takes numbers as value.
The input is not part of a form. Hence it doesn't get submitted, so validating during submission is not an option. I want the user to be unable to type in any characters other than numbers.
Is there a neat way to achieve this?
You can use HTML5 input type number to restrict only number entries:
<input type="number" name="someid" />
This will work only in HTML5 complaint browser. Make sure your html document's doctype is:
<!DOCTYPE html>
See also https://github.com/jonstipe/number-polyfill for transparent support in older browsers.
Update: There is a new and very simple solution for this:
It allows you to use any kind of input filter on a text
<input>, including various numeric filters. This will correctly handle Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations, non-typeable keys, and all keyboard layouts.
See this answer or try it yourself on JSFiddle.
For general purposes, you can have JS validation as below:
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : evt.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}<input name="someid" type="number" onkeypress="return isNumberKey(event)" />If you want to allow decimals replace the if-conditio" with this:
if (charCode > 31 && (charCode != 46 &&(charCode < 48 || charCode > 57)))
You can also use the pattern attribute in html5:
<input type="text" name="name" pattern="[0-9]" title="Title" />
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)))" />
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 following one line code as :
<input type="text" onkeypress="return /[0-9]/i.test(event.key)" >
It will accept numbers ony.
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:
Update 2018-03-12: Browser support is much better now it's supported by the following:
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.
function AllowOnlyNumbers(e) {
e = (e) ? e : window.event;
var clipboardData = e.clipboardData ? e.clipboardData : window.clipboardData;
var key = e.keyCode ? e.keyCode : e.which ? e.which : e.charCode;
var str = (e.type && e.type == "paste") ? clipboardData.getData('Text') : String.fromCharCode(key);
return (/^\d+$/.test(str));
}<h1>Integer Textbox</h1>
<input type="text" autocomplete="off" id="txtIdNum" onkeypress="return AllowOnlyNumbers(event);" />
<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!
<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">
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).
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.
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>
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:
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;
};
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" />
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 anhr@mail.ru">
<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
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.
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)"/>
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.
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]+">
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);"/>
Use <input type="number">, it only accepts inputs that are numbers.
Try submitting the two forms below with non number values.
<form>
<!-- some code -->
<input type="number">
<button>SUBMIT</button>
</form>Older browsers don’t support type=number. So we can validate it with JavaScript:
<form onsubmit=
"if (isNaN(document.getElementById('validatethis').value)) return false;">
<!-- some code -->
<input type="text" id="validatethis">
<button>SUBMIT</button>
</form>
The accepted answer is already good, however if your requirement is that you would like your user to be able to navigate their input (by using either the left or right cursor keys) and possibly amend their input (by using either the delete or the backspace key on the keyboard), you may choose to use this method.
Another benefit of this method is that accepts numbers from both the top row of the keyboard in addition to numbers from the numeric keypad.
The input HTML element will look something like this...
<input type="number"
onkeydown="return validateIsNumericInput(event)"
...
any other attributes for the input element
>
The JavaScript function will look like this:
/**
Checks the ASCII code input by the user is one of the following:
- Between 48 and 57: Numbers along the top row of the keyboard
- Between 96 and 105: Numbers in the numeric keypad
- Either 8 or 46: The backspace and delete keys enabling user to change their input
- Either 37 or 39: The left and right cursor keys enabling user to navigate their input
*/
function validateIsNumericInput(evt) {
var ASCIICode = (evt.which) ? evt.which : evt.keyCode
permittedKeys = [8, 46, 37, 39]
if ((ASCIICode >= 48 && ASCIICode <= 57) || (ASCIICode >= 96 && ASCIICode <= 105)) {
return true;
};
if (permittedKeys.includes(ASCIICode)) {
return true;
};
return false;
}
From my understanding, you want to only allow numerical values in a text input box. I also struggled with this logic as I am a beginner. This problem can be simply solved in ES6.Here is the most simplest solution I came up with:
function test(){
for (var i = 0; i < document.getElementById("element").value.length; i++) {
if (isNaN(document.getElementById("element").value[i])){
document.getElementById("element").value = '';
console.log(document.getElementById("element").value[i])
}
};
}
Please note that this code does not work for floating-point-numbers!
This seems to work in Vue. Basically removes any non-digit input.
<input type="number" @input="(event) => event.target.value = event.target.value.replace(/\D/g, '')" />
It handles decimals, commas, strings, backspace, pasting, etc.
You can tweak the regex to allow decimals and commas too, though not sure how that would work properly with the browser locale.
