A library component loaded from your own manifest fetches its lazy chunks from that manifest's folder
SPComponentLoader.loadComponent(manifest) loads a component from any manifest you hand it, and webpack inside that component resolves every lazy chunk against the folder its bundle was loaded from — the manifest's internalModuleBaseUrls. Publish the bundle and its manifest to a folder without the chunk.* files, and the app starts fine — then every import()-ed feature 404s on first use, which a smoke test that only opens the app never exercises. Copy all chunks next to the bundle, and make the smoke test open a lazy feature.
SPComponentLoader.loadComponent(manifest) načte komponentu z jakéhokoli manifestu, který mu předáš, a webpack uvnitř ní skládá adresu každého líně načítaného chunku ze složky, odkud se načetl její bundle – tedy z internalModuleBaseUrls toho manifestu. Když do složky publikuješ bundle s manifestem bez souborů chunk.*, appka naběhne normálně – a pak každá funkce za import() při prvním použití vrátí 404, což smoke test, který jen otevře appku, nikdy nevyzkouší. Zkopíruj všechny chunky k bundlu a ať smoke test otevře i líně načítanou funkci.
Symptom
The component renders. Charts, spreadsheet import, document preview — anything behind a dynamic import() — fails the first time a user opens it:
GET https://cdn.contoso.com/app/1.4.0/chunk.xlsx_4c1e0d6a9b7f3e2a1c5d.js 404The chunk exists — in the build's flat asset folder, not in the folder the manifest points at.
Cause
The SPFx loader requests the bundle from the manifest's internalModuleBaseUrls, and the bundle sets webpack's public path from the address of its own script (SPFx adds SetPublicPathCurrentScriptPlugin to the build). Chunk URLs are built from that public path — so point a manifest at a new folder and the chunks are expected there too. A packaging step that moves only the entry bundle and its manifest leaves them behind — in our case some eighty chunks (diagram rendering, spreadsheets, document conversion) that nothing at startup asked for.
Fix
- Copy every
chunk.*from the build's asset folder into the folder the manifest names — copy, not move, if the flat folder still serves other components. - Add the copy step even to components that have no chunks today; the first future
import()would otherwise break silently. - Make the post-release check open one lazy-loaded feature, not just the app. When the feature is costly or has side effects, load its chunk from the console instead: Load an SPFx bundle's lazy chunk from the browser console.
Notes
- Webpack composes a chunk's file name from two maps at runtime, so the full
chunk.<name>_<hash>.jsis often not present as a string in the bundle. When you check which chunks a bundle needs, search for the bare 20-hex hash. - Tempted to keep one shared copy of each chunk across versions? Decide by content, not by name: An SPFx chunk's file name is not its content.
- The same "breaks only on first use" shape bites CDN clean-ups: CDN pruning deleted the extension bundle the .sppkg still referenced.
loadComponentis part of the public@microsoft/sp-loaderAPI: SPComponentLoader class.