Function defaultLoad

lib/internal/modules/esm/load.js:62–116

* Node.js default load hook. * @param {string} url * @param {LoadContext} context * @returns {LoadReturn}

(url, context = kEmptyObject)

 * @returns {LoadReturn}
 */
function defaultLoad(url, context = kEmptyObject) {
  let responseURL = url;
  let {
    importAttributes,
    format,
    source,
  } = context;

  if (importAttributes == null && !('importAttributes' in context) && 'importAssertions' in context) {
    emitImportAssertionWarning();
    importAttributes = context.importAssertions;
    // Alias `importAssertions` to `importAttributes`
    context = {
      ...context,
      importAttributes,
    };
  }

  const urlInstance = new URL(url);

  throwIfUnsupportedURLScheme(urlInstance);

  if (urlInstance.protocol === 'node:') {
    source = null;
    format ??= 'builtin';
  } else if (format === 'addon') {
    // Skip loading addon file content. It must be loaded with dlopen from file system.
    source = null;
  } else if (format !== 'commonjs') {
    if (source == null) {
      ({ responseURL, source } = getSourceSync(urlInstance, context));
      context = { __proto__: context, source };
    }

    if (format == null) {
      // Now that we have the source for the module, run `defaultGetFormat` to detect its format.
      format = defaultGetFormat(urlInstance, context);

      if (format === 'commonjs') {
        // For backward compatibility reasons, we need to discard the source in
        // order for the CJS loader to re-fetch it.
        source = null;
      }
    }
  }

  validateAttributes(url, format, importAttributes);

  return {
    __proto__: null,
    format,
    responseURL,
    source,
  };
}
/**
 * @typedef LoadContext
 * @property {string} [format] A hint (possibly returned from `resolve`)