Previewing a release

The dev loop is not what ships: NODE_ENV is "development" and nothing is hashed. esdev preview serves the release output, which is where failures the dev loop is blind to show up — a package that hands over a different module under production, or a <link> pointing at a name hashing changed.

esdev build
esdev preview            # → http://127.0.0.1:4173
esdev preview --dir=dist --port=5000
esdev preview --config=deploy/esdev.json   # the site another project file describes

Preview serves existing output; it does not build. It serves the output the way a static host does: a missing path gets a 404 status, with the output's top-level 404.html as the page when it has one. Responses support ETag and Last-Modified revalidation (304) and HTTP range requests (206, or 416 when a range cannot be satisfied).

Single-page apps

A client-side router needs every route to load index.html. Pass --spa so that a missing path with no file extension gets index.html with a 200:

esdev preview --spa

Missing files with an extension, such as /app.js, still get a 404.

Server bundles

A server bundle has no static output to preview. Run it under esrun, as it will run in production.

The project's dev.server.proxy applies here too, so a page that calls /api reaches the same API server it does in the dev loop.

Any static folder, no packages

--dir serves whatever folder you point it at — no project, no esdev.json, no npx serve or python3 -m http.server. The folder needs an index.html at its root; everything else is served as-is, with the same 404 handling, --spa, validators, and ranges as above.

esdev preview --dir=./public        # → http://127.0.0.1:4173
esdev preview --dir=./dist --port=5000

Handy for a mock API's docs folder, a downloaded theme, or the dist/ of a tool that is not esdev build — anything with an entry document. Loopback only, like every endpoint esdev opens; Ctrl-C stops it.

For the rebuild-and-reload workflow, return to The dev loop.