When JSR transpiles a package to JS for distribution over npm.jsr.io, it produces mod.js files, which are a Deno convention (historical trivia: naming inspiration came from Go). Since the npm.jsr.io registry is intended for... well, npm, it makes more sense for those files to be named index.js. Also, a non-trivial amount of tooling in the npm ecosystem relies on index.js in their module resolution (even node and npm themselves), so it further improves compatibility in that area.
This is a tracking issue for a PR to follow.
When JSR transpiles a package to JS for distribution over npm.jsr.io, it produces mod.js files, which are a Deno convention (historical trivia: naming inspiration came from Go). Since the npm.jsr.io registry is intended for... well, npm, it makes more sense for those files to be named index.js. Also, a non-trivial amount of tooling in the npm ecosystem relies on index.js in their module resolution (even node and npm themselves), so it further improves compatibility in that area.
This is a tracking issue for a PR to follow.