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esbuild serve mode: static assets, CORS headers on the built-in server, and API proxy glue code
esbuild’s minimal dev server is fast but you must attach CORS headers manually for SPAs that call remote APIs during local demos.
1 min read
esbuildstaticcors
Cross-origin workers
Workers loaded from blob: URLs change effective origin semantics—test CORS against your API with the same build flags as production.
Source maps for minified bundles should not leak internal hostnames in CORS error pages.
CI smoke tests
Run headless browsers against `esbuild --serve` with the same env vars as developers to catch drift.
Snapshot response headers for OPTIONS on critical routes after each dependency upgrade.