How does Lichess parse PGN files/text?

[verbal scarab]

I'm creating a chess app, but the packages I've tried to use for parsing PGN files throw errors:
https://www.npmjs.com/package/pgn-parser
https://www.npmjs.com/package/cm-pgn

However, when I paste the same PGN into Lichess or open the file there, everything works fine. I was wondering how Lichess handles parsing PGN files, particularly in studies, since comments are important for my app

[vast dagger]

https://lichess.org/source

it's in scalachess

and chessops https://niklasf.github.io/chessops/modules/pgn.html

[verbal scarab]

Great, thanks for sharing! I'll take a closer look at both scalachess and chessops

[ripe arrow]

If you are building an app in JS/TS, you should probably already use the chess.js package, it has a built in PGN parser that works pretty well

[verbal scarab]

Yeah, I’m building a TypeScript app, and I was using the TypeScript version of that package, chess.ts. However, that parser, along with the others I mentioned earlier, was throwing errors. Today, I started using chessops, and it’s able to parse the PGN files that the other packages couldn’t handle.

[ripe arrow]

chess.ts is not the same package. I was talking about chess.js https://github.com/jhlywa/chess.js which is written in typescript. This package is maintained and quite popular so if you were using this one, it's weird you got errors using it 🤔