1. "Hur hur, sed piped with other tools already does this, you loser, why did you waste your time?"
2. "Cool, a different take on sed written in Javascript. They've written some basic doco and made a npm package, I might try it."
Ignore #1 online and in-person, be friends with #2.
People who adhere to type 1 behaviour are alien to me. I fundamentally don't understand what their motivation is to respond with such harsh criticism. You've liberated some close source, personal tool, into the public domain. There's some group of people, perhaps in the long-tail, that will use this tool, or learn from the source code. Clearly people have expressed interest in the tool (74 stars and 5 forks).
Again, ignore #1, friend #2.