Regex for input with numbers and commas

Question

I'm trying to limit input data.

My goal:

• only two symbols per input allowed: numbers and a comma
• first symbol only number (zero or more)
• amount of numbers is unlimited (zero or more)
• a dangling comma is allowed but only one

Test cases:

• 1,2,4 - ок
• 1221,212,4121212 - ок
• ,2,3 - not ок
• 1,2,3, - ок
• 11,21111,31111, - ок

I've hade something like this but it doesn't work properly

/^\d*(,\d*)*$/.test(value)

Appreciate any help!

Answer 1

You can use

/^(?:\d+(?:,\d+)*,?)?$/

See the regex demo. Details:

• ^ - start of string
• (?:\d+(?:,\d+)*,?)? - an optional non-capturing group:
  • \d+ - one or more digits
  • (?:,\d+)* - zero or more sequences of a comma and one or more digits
  • ,? - an optional comma
• $ - end of string.