Regex to validate comma-separated numbers with optional fractional parts

Question

Using JavaScript, I need to accept only numbers and commas.

The regex pattern I am using is as follows

 var pattern = /^[-+]?[0-9]+(\.[0-9]+)?$/;

How do I accept commas in the above pattern So that values like 3200 or 3,200 or 3,200.00 and so are valid?

There are similar questions that only partially deal with this:

• Regex validation for numbers with comma separator (only whole numbers with no fractional part)
• Decimal number regular expression, where digit after decimal is optional (no comma separation, fractional part limited to 1 digit)
• Javascript function need allow numbers, dot and comma (the dots, commas and digits are matched in any order)

Answer 1

Use the following regex:

^[-+]?(?:[0-9]+,)*[0-9]+(?:\.[0-9]+)?$

See regex demo

The basic change here is the addition of (?:[0-9]+,)* subpattern that matches:

• [0-9]+ - 1 or more digits
• , - a comma

0 or more times (thanks to * quantifier).

I also used non-capturing groups so that regex output is "cleaner".

If you need to check for 3-digit groups in the number, use

^[-+]?[0-9]+(?:,[0-9]{3})*(?:\.[0-9]+)?$

See another demo

Here, (?:,[0-9]{3})* matches 0 or more sequences of a comma and 3-digit substrings ([0-9]{3}). {3} is a limiting quantifier matching exactly 3 occurrences of the preceding subpattern.