Add space after commas only if it doesn't already?

Question

Is there a way to add a space after commas in a string only if it doesn\'t exist.

Example:

word word,word,word,

Would end up as

Answer 1

Just use a regular expression to replace all instances of "," not followed by a space with ", ".

str = "word word,word,word,"

str = str.gsub(/,([^ ])/, ', \1') # "word word, word, word,"