How to recover substrings from text in a post given UTF-8 indices?

[r002]

Hi everyone,

I'm new here, so apologies if this is a newbie question! I've been playing w/ the bsky APIs and ATProto for the past month and am currently trying to parse a hydrated post.

I have this:

but just need an easy way to map the did to the handle. I did read the docs and see here we're not supposed to use .slice() bc JS is utf-16 vs ATProto's utf-8.

So what is the best way to do this today? Basically, I just want a richText library function where I can put in the text and indices and get back the substring I'm interested in. Something like, .getText(text, 113, 134) and get back mmasnick.bsky.social. Do I just write my own? Is there already an existing helper function in the ATProto RichText library that I'm unaware of?

If someone could pls advise, I'd be grateful. TIA!! 🙏