A debugger bridge is implemented.
Open devtools://devtools/bundled/inspector.html?experiments=true&v8only=true&ws=127.0.0.1:9229/1 in Chrome to start debugging the javascript sources.
Note
The listening port can be changed in Project Settings, and a restart is required for it to take effect.
Project Settings > GodotJS > Debugger > Editor Port for Editor environment
Project Settings > GodotJS > Debugger > Runtime Port for Runtime environment.
Check Advanced Settings if they are not listed in Project Settings.