Back in 2018 I created that repo with a strawperson, and I feel that it's very necessary for streaming APIs where matches may occur across chunk boundaries and for as-you-type validation where you might want to notify the user when they type an invalid character but not if they're still typing out a potentially valid sequence. The repo itself documents much of the rationale, but the state of the JS world in that area hasn't hardly changed at all.
Thoughts?
I do want to note I'm by no means married to the names or the particular API, and am open to suggestions in that front. (Integration with iterables of UTF-8 and/or UCS-2 sequences is a must, though, as well as the ability to read strings.)