Generic JavaScript regex validating a positive number with or without commas as thousand separators and an optional fractional part

Question

I have following regex to validate numbers in input

var reg = /^\d+$/;

Now i want to allow ,(commas) and .(period) in number field as following will some one help me writing regex to allow following number format ?

10000000
10,000,000
10000000.00

should `10,000,000.00` be matched too? – nozzleman Dec 07 '16 at 19:34 — nozzleman, Dec 07 '16 at 19:34
and how many decimal places strictly 2 or variable number? – Damon Dec 07 '16 at 19:35 — Damon, Dec 07 '16 at 19:35
Will `/^\d+(?:,\d+)*(?:\.\d*)?$/` work for you? – anubhava Dec 07 '16 at 19:35 — anubhava, Dec 07 '16 at 19:35
Can't you simply just use ``? – Endless Dec 13 '16 at 21:10 — Endless, Dec 13 '16 at 21:10

score 4 · Accepted Answer · answered Dec 07 '16 at 19:36

4

You may use

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

If you only need to allow 2 digits after the decimal separator, replace (?:\.\d+)? with (?:\.\d{1,2})?.

Details:

^ - start of string
(?:\d{1,3}(?:,\d{3})*|\d+) - 2 alternatives:
- \d{1,3}(?:,\d{3})+ - 1 to 3 digits and one or more sequences of a comma and 3 digits
- \d+ - 1 or more digits
(?:\.\d+)? - an optional sequence of:
- \. - a dot
- \d+ - 1 or more digits
$

answered Dec 07 '16 at 19:36

Wiktor Stribiżew

after . last digits can only be 00, can you suggest how can do that ? – d-man Dec 07 '16 at 20:54
If you only allow `00` as the decimal part, replace `(?:\.\d+)?` with `(?:\.00)?` – Wiktor Stribiżew Dec 07 '16 at 21:03

score 1 · Answer 2 · answered Dec 07 '16 at 19:36

1

You could use

^((\d{1,2}(,\d{3})+)|(\d+)(\.\d{2})?)$

or

^((\d{1,2}(,\d{3})+)|(\d+))(\.\d{2})?$

if you want 10,000,000.00 to get matched to.

answered Dec 07 '16 at 19:36

nozzleman

2 Answers2