Function fetchModule

packages/vite/src/node/ssr/fetchModule.ts:24–116

(
  environment: DevEnvironment,
  url: string,
  importer?: string,
  options: FetchModuleOptions = {},
)

 * @experimental
 */
export async function fetchModule(
  environment: DevEnvironment,
  url: string,
  importer?: string,
  options: FetchModuleOptions = {},
): Promise<FetchResult> {
  if (
    url.startsWith('data:') ||
    isBuiltin(environment.config.resolve.builtins, url)
  ) {
    return { externalize: url, type: 'builtin' }
  }

  // handle file urls from not statically analyzable dynamic import
  const isFileUrl = url.startsWith('file://')

  if (isExternalUrl(url) && !isFileUrl) {
    return { externalize: url, type: 'network' }
  }

  // if there is no importer, the file is an entry point
  // entry points are always internalized
  if (!isFileUrl && importer && url[0] !== '.' && url[0] !== '/') {
    const { isProduction, root } = environment.config
    const { externalConditions, dedupe, preserveSymlinks } =
      environment.config.resolve

    const resolved = tryNodeResolve(url, importer, {
      mainFields: ['main'],
      conditions: externalConditions,
      externalConditions,
      external: [],
      noExternal: [],
      extensions: ['.js', '.cjs', '.json'],
      dedupe,
      preserveSymlinks,
      tsconfigPaths: false,
      isBuild: false,
      isProduction,
      root,
      packageCache: environment.config.packageCache,
      builtins: environment.config.resolve.builtins,
    })
    if (!resolved) {
      const err: any = new Error(
        `Cannot find module '${url}' imported from '${importer}'`,
      )
      err.code = 'ERR_MODULE_NOT_FOUND'
      throw err
    }
    const file = pathToFileURL(resolved.id).toString()
    const type = isFilePathESM(resolved.id, environment.config.packageCache)
      ? 'module'
      : 'commonjs'
    return { externalize: file, type }
  }

  url = unwrapId(url)