JavaScript validation: regex to validate numbers with comma

Question

How do I use JavaScript regex to validate numbers like this?

1,000
1,000.00
1000.00
1000

I tried this (the string used should not match):

test('2342342342sdfsdfsdf');

function test(t)
{
    alert(/\d{1,3}(,\d{3})*(\.\d\d)?|\.\d\d/.test(t));
}

but still gives me true.

I think this has already been answered: http://stackoverflow.com/questions/3455988/number-with-comma-separator-validation-regular-expression-is-required — Elad Lachmi, Mar 28 '11 at 07:52
@Elad I guess it's not the same: her we have a number where comma is the thousands separator, so 3 digits between each comma — bluish, Mar 28 '11 at 08:04
Your regular expression does not test for the start and end of a string! — epascarello, Jul 22 '14 at 23:52

Elian Ebbing · Answer 1 · 2011-03-28T08:24:18.980

If you want to test if the complete input string matches a pattern, then you should start your regex with ^ and end with $. Otherwise you are just testing if the input string contains a substring that matches the given pattern.

^ means "Start of the line"
$ means "End of the line"

In this case it means you have to rewrite you regex to:

/^(\d{1,3}(,\d{3})*(\.\d\d)?|\.\d\d)$/

If you would omit the extra parentheses, because otherwise the "|" would have lower precedence than the ^ and $, so input like "1,234.56abc" or "abc.12" would still be valid.

score 3 · Answer 2 · edited Mar 28 '12 at 22:38

3

I'm not sure what you mean by validate. But this might work.

//console.log is used in firebug.
var isNumber = function( str ){
    return !isNaN( str.toString().replace(/[,.]/g, '') );
}
console.log( isNumber( '1,000.00' ) === true );
console.log( isNumber( '10000' ) === true );
console.log( isNumber( '1,ooo.00' ) === false );
console.log( isNumber( 'ten' ) === false );
console.log( isNumber( '2342342342sdfsdfsdf') === false );

edited Mar 28 '12 at 22:38

wickedone

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answered Mar 28 '12 at 18:25

Larry Battle

9,008
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With this logic, if you add a value like: `1,,4` it'll pass as True – Yrineu Rodrigues Aug 09 '20 at 07:30

score 2 · Answer 3 · answered Mar 28 '11 at 08:01

2

try this

var number = '100000,000,000.00';
var regex = /^\d{1,3}(,?\d{3})*?(.\d{2})?$/g;
alert(regex.test(number));

answered Mar 28 '11 at 08:01

Liviu T.

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JavaScript validation: regex to validate numbers with comma

3 Answers3