Framework build output

Frameworks such as Nuxt, Nitro, SvelteKit and Astro import virtual modules like #imports that only the framework's own build can resolve. edgefit cannot follow those from your source, so for framework apps you build first and scan the output.

npx nuxi build --preset cloudflare_module
npx edgefit check --built .output/server

--built takes the output directory or its entry file:

npx edgefit check --built .output/server            # the directory
npx edgefit check --built .output/server/index.mjs  # or the entry file

--built and --entry cannot be used together.

You don't need --built when the entry is already inside a Nitro output, for example when wrangler's main is .output/server/index.mjs. edgefit sees the nitro.json next to it and scans the output as build output. SvelteKit's and Astro's outputs have no such marker, so always pass --built for them, for example --built .svelte-kit/cloudflare.

How the entry is found

For a directory, edgefit uses the main of a wrangler config inside it. Otherwise it looks for the first of these files:

• index.mjs
• index.js
• _worker.js
• _worker.js/index.js
• worker.js

From there it follows static and dynamic imports between the output chunks.

Turn on sourcemaps

Without sourcemaps, findings point into the build chunks, which is rarely where you want to fix anything. With them, each finding is mapped back to the original file and package, and the chunks it was reached through become its chain:

error    unsupported  navigator.locks.request  (workerd)
       does not exist on the target
       task-lock@2.1.0  node_modules/task-lock/index.js:2:26
       via .output/server/index.mjs > .output/server/chunks/nitro/nitro.mjs > .output/server/chunks/routes/index.mjs > task-lock

edgefit picks up a sourceMappingURL comment (inline or pointing to a file), or a .map file next to the chunk.

Nitro and Nuxt

Build with sourcemap: true. Nitro also empties the mappings of server sourcemaps unless you set experimental.sourcemapMinify: false.

When the maps have no mappings, the report adds a note saying so.

Without sourcemaps

Recent Nitro builds mark the code of every module in a chunk with //#region <path> comments. When a chunk has no sourcemap, edgefit reads those markers to name the package a finding belongs to, so the report says jose@6.2.12 instead of your code, and an ignore rule with package works.

The file and line still point into the chunk, because the markers name the original file but not the line inside it. Chunks without markers, such as those from older Nitro versions, stay unattributed.

error    unsupported  navigator.locks.request  (workerd)
       does not exist on the target
       jose@6.2.12  .output/server/_libs/jose.mjs:1875:34
       via .output/server/index.mjs > .output/server/_libs/jose.mjs > jose

Polyfills the build injected

Framework presets for edge runtimes replace Node modules with unenv polyfills. After the build, there is no node:fs import left to find, only the polyfill. With sourcemaps, edgefit recognizes code bundled from unenv's runtime/node and runtime/mock folders and reports it as mocked, located in the unenv file:

error    mocked  node:fs  (workerd)
       is replaced by an unenv polyfill in the build, where missing members throw or do nothing
       unenv@2.0.0-rc.24  node_modules/unenv/dist/runtime/node/internal/fs/fs.mjs:1:1
       via .output/server/index.mjs > .output/server/chunks/nitro/nitro.mjs > .output/server/chunks/routes/index.mjs > unenv

This is the only way to see these, which is one more reason to keep sourcemaps on. Nitro keeps the sources this needs by default.

If a polyfill is known to be fine for how you use it, lower the level or ignore it:

export default defineConfig({
  ignore: [{ package: 'unenv', api: 'node:process', reason: 'only process.env is used' }],
});