Regex in JavaScript for validating decimal numbers

Question

I want a regex in JavaScript for validating decimal numbers.

It should allow only up to two decimal places. For example, it should allow 10.89 but not 10.899.

It should also allow only one period (.). For example, it should allow 10.89 but not 10.8.9.

stackoverflow.com/q/468655/55209

Artem Koshelev
– Artem Koshelev

2012-04-05 06:48:38 +00:00
Commented Apr 5, 2012 at 6:48 — Artem Koshelev
– Artem Koshelev, Commented Apr 5, 2012 at 6:48
duplicate : stackoverflow.com/q/468655/55209

safarov
– safarov

2012-04-05 06:49:34 +00:00
Commented Apr 5, 2012 at 6:49 — safarov
– safarov, Commented Apr 5, 2012 at 6:49

zatatatata · Accepted Answer · 2012-04-05 08:32:16Z

54

Try the following expression: ^\d+\.\d{0,2}$ If you want the decimal places to be optional, you can use the following: ^\d+(\.\d{1,2})?$

EDIT: To test a string match in Javascript use the following snippet:

var regexp = /^\d+\.\d{0,2}$/;

// returns true
regexp.test('10.5')

edited Apr 5, 2012 at 8:32

answered Apr 5, 2012 at 6:48

zatatatata

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2 Comments

zatatatata Over a year ago

@micha, sorry fixed the typo in my first regexp

Marko Over a year ago

Use var regexp = /^\d+\.?\d{0,2}$/; if you want to have a optional commaseparator.

John Slegers · Accepted Answer · 2022-06-01 22:18:13Z

54

Positive decimals only

/^\d+(\.\d{1,2})?$/

Negative or positive decimals

/^-?\d+(\.\d{1,2})?$/

Demo

var regexp = /^\d+(\.\d{1,2})?$/;

console.log("POSITIVE ONLY");
console.log("'.74' returns " + regexp.test('.74'));
console.log("'7' returns " + regexp.test('7'));
console.log("'-4' returns " + regexp.test('-4'));
console.log("'10.5' returns " + regexp.test('10.5'));
console.log("'115.25' returns " + regexp.test('115.25'));
console.log("'-120.56' returns " + regexp.test('-120.56'));
console.log("'1535.803' returns " + regexp.test('1535.803'));
console.log("'153.14.5' returns " + regexp.test('153.14.5'));
console.log("'415351108140' returns " + regexp.test('415351108140'));
console.log("'415351108140.55' returns " + regexp.test('415351108140.55'));
console.log("'415351108140.556' returns " + regexp.test('415351108140.556'));

regexp = /^-?\d+(\.\d{1,2})?$/;

console.log("\n");
console.log("POSITIVE OR NEGATIVE");
console.log("'.74' returns " + regexp.test('.74'));
console.log("'7' returns " + regexp.test('7'));
console.log("'-4' returns " + regexp.test('-4'));
console.log("'10.5' returns " + regexp.test('10.5'));
console.log("'115.25' returns " + regexp.test('115.25'));
console.log("'-120.56' returns " + regexp.test('-120.56'));
console.log("...");

Explanation

/ / : the beginning and end of the expression
^ : whatever follows should be at the beginning of the string you're testing
\d+ : there should be at least one digit
( )? : this part is optional
\. : here goes a dot
\d{1,2} : there should be between one and two digits here
$ : whatever precedes this should be at the end of the string you're testing

If you also want to support negative decimals, you just need to add -? right after the ^, which means that an optional minus sign is allowed there as well.

Tip

You can use regexr.com or regex101.com for testing regular expressions directly in the browser!

edited Jun 1, 2022 at 22:18

answered Feb 12, 2018 at 9:48

John Slegers

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3 Comments

KylianMbappe Over a year ago

How would I extend this to accept negative numbers as well?

John Slegers Over a year ago

@KylianMbappe : I just updated my answer to add support for negative decimals

Yasser CHENIK Over a year ago

Here is a better solution for me /^\d{0,13}(\.\d{1,2}0*)?$/.test(yourNumber) to allow 10.1200 that you can remove using Number(yourNumber.toFixed(2)) but only when the condition is correct !

noob · Accepted Answer · 2012-04-05 06:49:46Z

43

^\d+(\.\d{1,2})?$

will allow:

244
10.89
9.5

will disallow:

10.895
10.
10.8.9

answered Apr 5, 2012 at 6:49

noob

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2 Comments

zatatatata Over a year ago

@ShardaprasadSoni see my post for an example

Kaloyan Stamatov Over a year ago

If I type 0000.100 which will be invalid decimal what the regExp should be?

Nisha · Accepted Answer · 2013-12-10 09:54:59Z

4

Numbers with at most 2 decimal places:

/^\d+(?:\.\d{1,2})?$/

This should work fine. Please try out :)

answered Dec 10, 2013 at 9:54

Nisha

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1 Comment

JTCon Over a year ago

How can I set the max decimals with a variable? Thanks

Paul J Abernathy · Accepted Answer · 2016-04-07 19:41:08Z

4

I found that I could use

^\d+(\.\d+)?$

for more than two decimal places.

answered Apr 7, 2016 at 19:41

Paul J Abernathy

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Comments

Andrej · Accepted Answer · 2017-11-25 10:28:39Z

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 custom filter of input of an float number with decimal pointer and limitation to 2 digit after decimal pointer:

<!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>Float field</h1>
<input id="Float" 
	onchange="javascript: onChangeFloat(this)"
	onblur="inputKeyFilter.isNaN(parseFloat(this.value), this);"
/>
<script>
	function CreateFloatFilterCustom(elementID, onChange, onblur){
		try{
			inputKeyFilter.Create(elementID
				, onChange
				, function(elementInput, value){//customFilter
					if(value.match(/^(-?\d*)((\.(\d{0,2})?)?)$/i) == null){
						inputKeyFilter.TextAdd(isRussian() ?
								"Допустимый формат: -[0...9].[0...9] или -[0...9]e-[0...9]. Например: -12.34 1234"
								: "Acceptable formats: -[0...9].[0...9] or -[0...9]e-[0...9]. Examples: -12.34 1234"
							, elementInput);
						return false;
					}
					return true;
				}
				, onblur
			)
		} catch(e) {
			consoleError("Create float filter failed. " + e);
		}
	}
	
	CreateFloatFilterCustom("Float");
	
	function onChangeFloat(input){
		inputKeyFilter.RemoveMyTooltip();
		var elementNewFloat = document.getElementById("NewFloat");
		var float = parseFloat(input.value);
		if(inputKeyFilter.isNaN(float, input)){
			elementNewFloat.innerHTML = "";
			return;
		}
		elementNewFloat.innerHTML = float;
	}
</script>
 New float: <span id="NewFloat"></span>
</body>
</html>

Also see my page example of the input key filter

replace from /^(-?\d*)((\.(\d{0,2})?)?)$/i to /^(-?\d{0,6})((\.(\d*)?)?)$/i

Harshit Sinha · Accepted Answer · 2016-08-05 06:50:36Z

3

Try a regular expression like this:

(?=[^\0])(?=^([0-9]+){0,1}(\.[0-9]{1,2}){0,1}$)

Allowed: 1, 10.8, 10.89, .89, 0.89, 1000

Not Allowed: 20. , 50.89.9, 12.999, ., Null character Note this works for positive numbers

answered Aug 5, 2016 at 6:50

Harshit Sinha

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Comments

Lorenzo Borelli · Accepted Answer · 2022-02-01 10:41:10Z

3

Since you asked for decimal numbers validation, for completeness' sake, I'd use a regex that doesn't allow strings like 06.05.

^((0(\.\d{1,2})?)|([1-9]\d*(\.\d{1,2})?))$

Slightly more complicated, but returns false in that case.

Edit:

^-?((0(\.\d{1,2})?)|([1-9]\d*(\.\d{1,2})?))$

if you want negative numbers as well.

edited Feb 1, 2022 at 10:41

answered Dec 17, 2019 at 16:05

Lorenzo Borelli

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2 Comments

ptent Over a year ago

This actually does not handle decimals in range [0, 1)

Lorenzo Borelli Over a year ago

It does, test here regex101.com. Particularly, this first half does (0(\.\d{1,2})?). Or at least it does up to 2 decimal places like OP asked.

Bhumin Vadalia · Accepted Answer · 2013-07-29 16:35:40Z

0

as compared from the answer gven by mic... it doesnt validate anything in some of the platforms which i work upon... to be precise it doesnt actually work out in Dream Viewer..

hereby.. i re-write it again..which will work on any platform.. "^[0-9]+(.[0-9]{1,2})?$".. thnkss..

answered Jul 29, 2013 at 16:35

Bhumin Vadalia

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Comments

Bhanu Pratap · Accepted Answer · 2019-05-06 10:39:41Z

0

 function CheckValidAmount() {
        var amounttext = document.getElementById('txtRemittanceNumber').value;            
        if (!(/^[-+]?\d*\.?\d*$/.test(amounttext))){
            alert('Please enter only numbers into amount textbox.')
            document.getElementById('txtRemittanceNumber').value = "10.00";
        }
    }

This is the function which will take decimal number with any number of decimal places and without any decimal places.

Thanks ... :)

edited May 6, 2019 at 10:39

answered Sep 6, 2016 at 18:39

Bhanu Pratap

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2 Comments

RamenChef Over a year ago

Can you post the code as text rather than an image?

Darksymphony Over a year ago

for what did you used var amount = parseFloat(amounttext); if later you are using test(amounttext) and amount is not used anywhere?

Cato Minor · Accepted Answer · 2019-06-22 10:35:16Z

0

The schema for passing the value in as a string. The regex will validate a string of at least one digit, possibly followed by a period and exactly two digits:

{
    "type": "string",
    "pattern": "^[0-9]+(\\.[0-9]{2})?$"
}

The schema below is equivalent, except that it also allows empty strings:

{
    "type": "string",
    "pattern": "^$|^[0-9]+(\\.[0-9]{2})?$"
}

edited Jun 22, 2019 at 10:35

Cato Minor

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answered Jun 22, 2019 at 8:11

Shobhit Pokhriyal

211 bronze badge

Comments

Tobi · Accepted Answer · 2012-04-05 06:48:39Z

-3

Does this work?

[0-9]{2}.[0-9]{2}

answered Apr 5, 2012 at 6:48

Tobi

1,4381 gold badge13 silver badges26 bronze badges

1 Comment

noob Over a year ago

. stands for any character | [0-9] is the same as \d

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Regex in JavaScript for validating decimal numbers

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Positive decimals only

Negative or positive decimals

Demo

Explanation

Tip

3 Comments

2 Comments

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12 Answers 12

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Positive decimals only

Negative or positive decimals

Demo

Explanation

Tip

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