Check whether a value is a number in JavaScript or jQuery

Question

Possible Duplicate:
Validate numbers in JavaScript - IsNumeric()

var miscCharge = $("#miscCharge").val();

I want to check misCharge is number or not. Is there any method or easy way in jQuery or JavaScript to do this?

HTMl is

<g:textField name="miscCharge"  id ="miscCharge" value="" size="9" max="100000000000" min="0" />

http://stackoverflow.com/questions/18082/validate-numbers-in-javascript-isnumeric — jon3laze, Jun 23 '11 at 05:15

score 196 · Accepted Answer · answered Jun 23 '11 at 05:14

196

function isNumber(n) {
  return !isNaN(parseFloat(n)) && isFinite(n);
}

answered Jun 23 '11 at 05:14

zad

15

This is even better: `return !isNaN(+n) && isFinite(n)` since for a numeric string with trailing letters the parseFloat | parseInt will return true and the second check isFInite will return false. While with unary `+` it will fail immediately. – Arman May 20 '13 at 16:29
11

"!isNaN(+n) && isFinite(n)" classifies the empty string as a number – thenickdude Aug 29 '13 at 03:03
3

I'm not sure if this is intended, but isNumber( ['5'] ) would also return true - but it's not a number, it's an array containing a number. – Katai Jun 25 '16 at 19:59
1

In one line: +str + '' === str – basil Sep 12 '18 at 11:49

cwallenpoole · Answer 2 · 2014-10-15T18:47:06.467

34

You've an number of options, depending on how you want to play it:

isNaN(val)

Returns true if val is not a number, false if it is. In your case, this is probably what you need.

isFinite(val)

Returns true if val, when cast to a String, is a number and it is not equal to +/- Infinity

/^\d+$/.test(val)

Returns true if val, when cast to a String, has only digits (probably not what you need).

edited Oct 15 '14 at 18:47

answered Jun 23 '11 at 05:32

cwallenpoole

1

vote down because Your regex does not work if `val` is `-1` or `1.5` – Sang Sep 12 '18 at 08:33
Worth noting that evaluation of an empty string is not what you'd expect: `isNaN('') == false` and `isFinite('') == true` – Derek Soike Dec 20 '18 at 18:34
@transang Indeed, otherwise using regex is probably the only reliable way if you want to test integers – Kirill G. Mar 21 '19 at 08:04

score 6 · Answer 3 · answered Jun 23 '11 at 05:33

6

there is a function called isNaN it return true if it's (Not-a-number) , so u can check for a number this way

if(!isNaN(miscCharge))
{
   //do some thing if it's a number
}else{
   //do some thing if it's NOT a number
}

hope it works

answered Jun 23 '11 at 05:33

Buffon

`isNaN(null)` returns `false`, `isNaN("")` returns `false` – Duc Filan Nov 14 '18 at 06:11
`isNaN(true)` and `isNaN(false)` also return false – Roberto Maldonado Dec 12 '18 at 00:39

3 Answers3