One comma in space

Question

Find, for example in

yyyy , yyyy

yyyy,yyyy

yyyy, yyyy

yyyy ,yyyy

the pattern between yyyy and yyyy.

I've tried:

(\s*,{1}\s*)

but this will also match

yyyy,,yyyy.

Demo

What is missing?

Answer 1

Using lookarounds:

(?<![,\s])\s*,\s*(?![,\s])

• (?<![,\s]) is a negative lookbehind (?<!pattern). In this case, "not preceded by a comma or a whitespace"
• (?![,\s]) is a negative lookahead (?!pattern). In this case, "not followed by a comma or a whitespace"