Function cjsPreparseModuleExports

lib/internal/modules/esm/translators.js:421–467

* Pre-parses a CommonJS module's exports and re-exports. * @param {string} filename - The filename of the module. * @param {string} [source] - The source code of the module. * @param {string} [format] * @returns {{module: CJSModule, exportNames: string[]}}

(filename, source, format)

 * @returns {{module: CJSModule, exportNames: string[]}}
 */
function cjsPreparseModuleExports(filename, source, format) {
  const module = cjsEmplaceModuleCacheEntry(filename);
  if (module[kModuleExportNames] !== undefined) {
    return { module, exportNames: module[kModuleExportNames] };
  }

  if (source === undefined) {
    ({ source } = loadSourceForCJSWithHooks(module, filename, format));
  }
  module[kModuleSource] = source;

  debug(`Preparsing exports of ${filename}`);
  const { 0: exportNames, 1: reexports } = cjsParse(source);

  // Set first for cycles.
  module[kModuleExportNames] = exportNames;

  // If there are any re-exports e.g. `module.exports = { ...require(...) }`,
  // pre-parse the dependencies to find transitively exported names.
  if (reexports.length) {
    module.filename ??= filename;
    module.paths ??= CJSModule._nodeModulePaths(dirname(filename));

    for (let i = 0; i < reexports.length; i++) {
      debug(`Preparsing re-exports of '${filename}'`);
      const reexport = reexports[i];
      let resolved;
      let format;
      try {
        ({ format, filename: resolved } = resolveForCJSWithHooks(reexport, module, false, kShouldNotSkipModuleHooks));
      } catch (e) {
        debug(`Failed to resolve '${reexport}', skipping`, e);
        continue;
      }

      if (format === 'commonjs' ||
        (!BuiltinModule.normalizeRequirableId(resolved) && findLongestRegisteredExtension(resolved) === '.js')) {
        const { exportNames: reexportNames } = cjsPreparseModuleExports(resolved, undefined, format);
        for (const name of reexportNames) {
          exportNames.add(name);
        }
      }
    }
  }

  return { module, exportNames };
}

// Strategy for loading a node builtin CommonJS module that isn't
// through normal resolution