When matching "product product name cat1" with this regex I get " product name" with a leading blank, of course I could trim in javascript but is there a way to modify regex to not catch that blank ?
(product)((\s+)(.(?!cat1|cat2))+)
Another way to look at it is to use a non greedy quantifier (.*?) in a single capture group, and match either cat1 or cat2 if you are only interested in product name
\bproduct\s+(.*?)\s+cat[12]\b
You can use
(product)(\s+)((?:(?!cat1|cat2).)+)
See the regex demo.
Note:
(\s+).