checking if number entered is a digit in jquery

Question

I have a simple textbox in which users enter number.
Does jQuery have a isDigit function that will allow me to show an alert box if users enter something other than digits?

The field can have decimal points as well.

so you mean numbers and not digits ?

Francisco Corrales Morales
– Francisco Corrales Morales

2014-09-16 19:33:52 +00:00
Commented Sep 16, 2014 at 19:33 — Francisco Corrales Morales
– Francisco Corrales Morales, Commented Sep 16, 2014 at 19:33

karim79 · Accepted Answer · 2009-08-13 15:50:38Z

88

I would suggest using regexes:

var intRegex = /^\d+$/;
var floatRegex = /^((\d+(\.\d *)?)|((\d*\.)?\d+))$/;

var str = $('#myTextBox').val();
if(intRegex.test(str) || floatRegex.test(str)) {
   alert('I am a number');
   ...
}

Or with a single regex as per @Platinum Azure's suggestion:

var numberRegex = /^[+-]?\d+(\.\d+)?([eE][+-]?\d+)?$/;
var str = $('#myTextBox').val();
if(numberRegex.test(str)) {
   alert('I am a number');
   ...
}

edited Aug 13, 2009 at 15:50

answered Aug 13, 2009 at 15:26

karim79

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2 Comments

Omnipresent Over a year ago

the number can have decimals also. 5001.10 should be acceptable

Platinum Azure Over a year ago

Should have specified that. :-) You can use a regex like this for ALL (well, many) possible numbers: /^[+-]?\d+(\.\d+)?([eE][+-]?\d+)?$/ This will allow for decimals, signs, and even scientific notation on the end if you want. You can remove various parts as you need to (Google Perl-style regular expressions if you need help figuring out which part is what, but it should be fairly intuitive).

Plutor · Accepted Answer · 2009-08-13 15:34:29Z

79

Forget regular expressions. JavaScript has a builtin function for this: isNaN():

isNaN(123)           // false
isNaN(-1.23)         // false
isNaN(5-2)           // false
isNaN(0)             // false
isNaN("100")         // false
isNaN("Hello")       // true
isNaN("2005/12/12")  // true

Just call it like so:

if (isNaN( $("#whatever").val() )) {
    // It isn't a number
} else {
    // It is a number
}

answered Aug 13, 2009 at 15:34

Plutor

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5 Comments

Ateş Göral Over a year ago

isNaN won't ensure your input doesn't contain whitespace. isNaN(" 42 ") === false

doomspork Over a year ago

You can trim the whitespace with something like : YouValue.replace(/^\s\s*/, '').replace(/\s\s*$/, ''); More trim implementations : blog.stevenlevithan.com/archives/faster-trim-javascript

system PAUSE Over a year ago

Interesting approach, but personally I think the regex is clearer than the double negative (not a Not-a-Number is a number). Although I'd be inclined to put the regex into a nice utility function isDigit().

NickFitz Over a year ago

@karim79: it's not the case that isNaN won't accept a string argument. isNaN("42") returns false, isNaN("42.2") returns false, isNaN("42.2.3") returns true. The documentation at developer.mozilla.org/en/Core_JavaScript_1.5_Reference/… states that "isNaN attempts to convert the passed parameter to a number. If the parameter can't be converted, it returns true; otherwise, it returns false".

Sohil Desai Over a year ago

isNaN() is not reliable function to check valid numbers because it also returns false for boolean values for e.g. isNaN(true) -> return value = false

Dan · Accepted Answer · 2014-09-11 13:42:16Z

13

there is a simpler way of checking if a variable is an integer. you can use $.isNumeric() function. e.g.

$.isNumeric( 10 );     // true

this will return true but if you put a string in place of the 10, you will get false.

I hope this works for you.

edited Sep 11, 2014 at 13:42

Dan

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answered Oct 24, 2013 at 10:45

Yoweli Kachala

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1 Comment

TarangP Over a year ago

The signature '(value: any): boolean' of '$.isNumeric' is deprecated.ts(6387)

M Arif · Accepted Answer · 2014-04-24 13:24:29Z

2

Following script can be used to check whether value is valid integer or not.

  function myFunction() {
    var a = parseInt("10000000");
    if (!isNaN(a) && a <= 2147483647 && a >= -2147483647){
    alert("is integer"); 
    } else {
     alert("not integer"); 
    }
}

answered Apr 24, 2014 at 13:24

M Arif

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Comments

PodTech.io · Accepted Answer · 2016-07-06 17:27:21Z

2

var yourfield = $('fieldname').val();

if($.isNumeric(yourfield)) { 
        console.log('IM A NUMBER');
} else { 
        console.log('not a number');
}

JQUERY DOCS:

https://api.jquery.com/jQuery.isNumeric/

answered Jul 6, 2016 at 17:27

PodTech.io

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Comments

Ateş Göral · Accepted Answer · 2009-08-13 15:28:26Z

1

Value validation wouldn't be a responsibility of jQuery. You can use pure JavaScript for this. Two ways that come to my mind are:

/^\d+$/.match(value)
Number(value) == value

answered Aug 13, 2009 at 15:28

Ateş Göral

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3 Comments

system PAUSE Over a year ago

Since your second example uses == and not ===, wouldn't type coercion on the right-hand-side cause the expression to be true always?

PC. Over a year ago

Don't know why no-one upvoated this answer. I used Number(value).... Its perfect.

Ateş Göral Over a year ago

@systemPAUSE The mention of user input and "digits" makes me think that the value is a string and the reason for the ==.

Lars Andren · Accepted Answer · 2010-09-15 07:07:57Z

With jQuery's validation plugin you could do something like this, assuming that the form is called form and the value to validate is called nrInput

$("form").validate({
            errorElement: "div",
            errorClass: "error-highlight",
            onblur: true,
            onsubmit: true,
            focusInvalid: true,
            rules:{
                'nrInput': {
                    number: true,
                    required: true
                }
            });

This also handles decimal values.

k2fl · Accepted Answer · 2014-05-29 06:40:26Z

1

String.prototype.isNumeric = function() {
    var s = this.replace(',', '.').replace(/\s+/g, '');
return s == 0 || (s/s);
}

usage

'9.1'.isNumeric() -> 1
'0xabc'.isNumeric() -> 1
'10,1'.isNumeric() -> 1
'str'.isNumeric() -> NaN

answered May 29, 2014 at 6:40

k2fl

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Comments

Community · Accepted Answer · 2020-06-20 09:12:55Z

0

jQuery is a set of JavaScript functions, right? So you could use JavaScript's regular expression support to validate the string. You can put this in a jQuery callback if you like, too, since those just take anonymously-declared function bodies and the functions are still JavaScript.

Link: http://www.regular-expressions.info/javascript.html

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Aug 13, 2009 at 15:27

Platinum Azure

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Comments

Sandip Singh · Accepted Answer · 2015-07-03 06:22:41Z

0

$(document).ready(function () {



    $("#cust_zip").keypress(function (e) {
        //var z = document.createUserForm.cust_mobile1.value;
        //alert(z);
        if (e.which != 8 && e.which != 0 && (e.which < 48 || e.which > 57)) {

            $("#errmsgzip").html("Digits Only.").show().fadeOut(3000);
            return false;
        }
    });
});

answered Jul 3, 2015 at 6:22

Sandip Singh

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1 Comment

namezero Over a year ago

Could you also add an explanation rather than just posting code?

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