Method fetchUpdate

packages/vite/src/shared/hmr.ts:264–308

(update: Update)

  }

  private async fetchUpdate(update: Update): Promise<(() => void) | undefined> {
    const { path, acceptedPath, firstInvalidatedBy } = update
    const mod = this.hotModulesMap.get(path)
    if (!mod) {
      // In a code-splitting project,
      // it is common that the hot-updating module is not loaded yet.
      // https://github.com/vitejs/vite/issues/721
      return
    }

    let fetchedModule: ModuleNamespace | undefined
    const isSelfUpdate = path === acceptedPath

    // determine the qualified callbacks before we re-import the modules
    const qualifiedCallbacks = mod.callbacks.filter(({ deps }) =>
      deps.includes(acceptedPath),
    )

    if (isSelfUpdate || qualifiedCallbacks.length > 0) {
      const disposer = this.disposeMap.get(acceptedPath)
      if (disposer) await disposer(this.dataMap.get(acceptedPath))
      try {
        fetchedModule = await this.importUpdatedModule(update)
      } catch (e) {
        this.warnFailedUpdate(e, acceptedPath)
      }
    }

    return () => {
      try {
        this.currentFirstInvalidatedBy = firstInvalidatedBy
        for (const { deps, fn } of qualifiedCallbacks) {
          fn(
            deps.map((dep) =>
              dep === acceptedPath ? fetchedModule : undefined,
            ),
          )
        }
        const loggedPath = isSelfUpdate ? path : `${acceptedPath} via ${path}`
        this.logger.debug(`hot updated: ${loggedPath}`)
      } finally {
        this.currentFirstInvalidatedBy = undefined
      }
    }
  }
}