CODEWITHSUNDEEP
javascriptjqueryregexnumbersdecimal
Shardaprasad Soni
Shardaprasad Soni

Reputation: 541

Regex in JavaScript for validating decimal numbers

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.

Upvotes: 39

Views: 172981

Answers (12)

John Slegers
John Slegers

Reputation: 47081

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

  1. / / : the beginning and end of the expression
  2. ^ : whatever follows should be at the beginning of the string you're testing
  3. \d+ : there should be at least one digit
  4. ( )? : this part is optional
  5. \. : here goes a dot
  6. \d{1,2} : there should be between one and two digits here
  7. $ : 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!

Upvotes: 54

Lorenzo Borelli
Lorenzo Borelli

Reputation: 127

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.

Upvotes: 3

Shobhit Pokhriyal
Shobhit Pokhriyal

Reputation: 21

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

Upvotes: 0

Bhanu Pratap
Bhanu Pratap

Reputation: 1761

 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 ... :)

Upvotes: 0

Andrej
Andrej

Reputation: 707

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

Upvotes: 4

Harshit Sinha
Harshit Sinha

Reputation: 31

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

Upvotes: 3

Paul J Abernathy
Paul J Abernathy

Reputation: 1003

I found that I could use

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

for more than two decimal places.

Upvotes: 4

Nisha
Nisha

Reputation: 685

Numbers with at most 2 decimal places:

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

This should work fine. Please try out :)

Upvotes: 4

Bhumin Vadalia
Bhumin Vadalia

Reputation: 271

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..

Upvotes: 0

zatatatata
zatatatata

Reputation: 4821

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')

Upvotes: 54

noob
noob

Reputation: 9202

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

will allow:

  1. 244
  2. 10.89
  3. 9.5

will disallow:

  1. 10.895
  2. 10.
  3. 10.8.9

Upvotes: 43

Tobi
Tobi

Reputation: 1438

Does this work?

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

Upvotes: -3

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