Regex of max 5 decimal separate by + - html

Question

i'm trying to make a regex to add to a input pattern (HTML) to check if is valid,
it need to be valid only if the input contain a string composed by decimal(with 1 or 2 number after comma) or integer number separated by a +
and maximum of 5 number
and it can not start or end with a + or it can not be possible to have a number with comma without number after (i use comma instead of dot for decimal)
for example
10+5,1+6,20 OK
10 OK
6+4+8,9+3+9+3 NO
10,2+4+6+ NO
10,+5 NO
i've tried with something like this but id doesn't work very well
((\d{1,3}|(\d*,\d{1,2})*)+(\+)?){1,5}
also i've tried with this:
^((\s*)|([0-9]\d{0,9}(\,\d{1,2})?%?))*(\+((\s*)|([0-9]\d{0,9}(\,\d{1,2})?%?))+){0,4}$
but it doesn't work very well with the 2 digit max for the decimal and ending +
any suggestions ??
i've made some test here:
https://regexr.com/5jsfv
it should pass the first 3 and faile on the last 4
thanks

Answer 1

You can use
^\d+(?:,\d{1,2})?(?:\+\d+(?:,\d{1,2})?){0,4}$
In the HTML pattern attribute use it as
pattern="\d+(?:,\d{1,2})?(?:\+\d+(?:,\d{1,2})?){0,4}"
See the regex demo.
NOTE: If you want to limit the number of digits in the integer part to be max 3, replace the \d+ with \d{1,3}:
^\d{1,3}(?:,\d{1,2})?(?:\+\d{1,3}(?:,\d{1,2})?){0,4}$
Details:
^ - start of string (implicit in pattern regex)
\d+(?:,\d{1,2})? - one or more digits and then an optional sequence of a , and one or two digits
(?:\+\d+(?:,\d{1,2})?){0,4} - zero to four occurrences of a + char followed with one or more digits and then an optional sequence of a , and one or two digits
$ - end of string (implicit in pattern regex)