Javascript Regex for decimals

Question

In Javascript, I am trying to validate a user input to be only valid decimals

I have the following JSFiddle that shows the regex I currently have

http://jsfiddle.net/FCHwx/

var regex = /^[0-9]+$/i;
var key = '500.00';
if (key.match(regex) != null) {
    alert('legal');
}
else {
    alert('illegal');
}

This works fine for integers. I need to also allow decimal numbers (i.e. up to 2 decimal places)

I have tried many of the regex's that can be found on stackoverflow e.g. Simple regular expression for a decimal with a precision of 2

but none of them work for this use case

What am I doing wrong?

Solution 1

This should be work

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

Solution 2

Have you tried this?

var regex = /^[0-9]+\.[0-9]{0,2}$/i;

Solution 3

I recommend you to not use REGEX for this, but use a simple !isNaN:

console.log(!isNaN('20.13')); // true
console.log(!isNaN('20')); // true
console.log(!isNaN('20kb')); // false

Comments

[Admin]

The question you linked to seems to do exactly what you want. Can you explain why those don't work, including showing the input that they fail on?

[Wouter J]

you can use \d instead of [0-9] too, it don't think it makes much difference, but I think it is a good practise to use those predefined character classes

[Wouter J]

the 3 means 3 decimals, he wants only 2.

[ChrisCa]

it doesn't seem to - try it in the jsfiddle above

[Barney]

@ChrisCa yes it does. Besides, 108 StackOverflow users can't be wrong, can they? ;)

[ChrisCa]

the one you link to works - it is slightly different to the one above (it has a /i on the end which seems to do the trick - thanks

[simple-thomas]

right, thought it meant 3 chars in total minimum

[stema]

@ChrisCa the i modifier has no influence here, it changes letters to match case independent, no letters, no influence on the regex.

[ChrisCa]

yeah - i did try that one - I even linked to it in the question. but it needs a little tweak to work in my use case (the /i).

[stema]

This would allow also "1." as valid input.

[stema]

@ChrisCa, for me it makes no difference (as it should) jsfiddle

[ChrisCa]

the reg ex linked to in the other question doesn't have the trailing slash that your jsfiddle has - that seems to be the problem