Function extractExportsData

packages/vite/src/node/optimizer/index.ts:1112–1190

(
  environment: Environment,
  filePath: string,
)

}

export async function extractExportsData(
  environment: Environment,
  filePath: string,
): Promise<ExportsData> {
  await init

  const { optimizeDeps } = environment.config

  const rolldownOptions = optimizeDeps.rolldownOptions ?? {}
  if (optimizeDeps.extensions?.some((ext) => filePath.endsWith(ext))) {
    // For custom supported extensions, build the entry file to transform it into JS,
    // and then parse with es-module-lexer. Note that the `bundle` option is not `true`,
    // so only the entry file is being transformed.
    const { plugins: pluginsFromConfig = [], ...remainingRolldownOptions } =
      rolldownOptions
    const plugins = await asyncFlatten(arraify(pluginsFromConfig))
    plugins.unshift({
      name: 'externalize',
      resolveId(id, importer) {
        if (importer !== undefined) {
          return { id, external: true }
        }
      },
    })
    const build = await rolldown({
      ...remainingRolldownOptions,
      plugins,
      input: [filePath],
      // TODO: remove this and enable rolldown's CSS support later
      moduleTypes: {
        '.css': 'js',
        ...remainingRolldownOptions.moduleTypes,
      },
    })
    const result = await build.generate({
      ...rolldownOptions.output,
      format: 'esm',
      sourcemap: false,
    })
    const [, exports, , hasModuleSyntax] = parse(result.output[0].code)
    return {
      hasModuleSyntax,
      exports: exports.map((e) => e.n),
    }
  }

  let parseResult: ReturnType<typeof parse>
  let usedJsxLoader = false

  const entryContent = fs.readFileSync(filePath, 'utf-8')
  try {
    parseResult = parse(entryContent)
  } catch {
    const lang = rolldownOptions.moduleTypes?.[path.extname(filePath)] || 'jsx'
    debug?.(
      `Unable to parse: ${filePath}.\n Trying again with a ${lang} transform.`,
    )
    if (lang !== 'jsx' && lang !== 'tsx' && lang !== 'ts') {