The JSON format is in (JavaScript) source maps format -- the .debug_line content.
It is planned to implement serialize and extends the JSON with one additional field: x-scopes. See info at https://gist.github.com/yurydelendik/802f36983d50cedb05f984d784dc5159 and https://gist.github.com/yurydelendik/10f3c99879e9459259a6aaf79f39215c.
cargo +nightly build --target=wasm32-unknown-unknown --lib --release
cp ./target/wasm32-unknown-unknown/release/dwarf_to_json.wasm \
$DEBUGGER_HTML/assets/wasm/