transform: async()

in packages/metro-transform-worker/src/index.js [668:726]
52 lines of code
6 McCabe index (conditional complexity)

  transform: async (
    config: JsTransformerConfig,
    projectRoot: string,
    filename: string,
    data: Buffer,
    options: JsTransformOptions,
  ): Promise<TransformResponse> => {
    const context: TransformationContext = {
      config,
      projectRoot,
      options,
    };
    const sourceCode = data.toString('utf8');

    const {unstable_dependencyMapReservedName} = config;
    if (unstable_dependencyMapReservedName != null) {
      const position = sourceCode.indexOf(unstable_dependencyMapReservedName);
      if (position > -1) {
        throw new SyntaxError(
          'Source code contains the reserved string `' +
            unstable_dependencyMapReservedName +
            '` at character offset ' +
            position,
        );
      }
    }

    if (filename.endsWith('.json')) {
      const jsonFile: JSONFile = {
        filename,
        inputFileSize: data.length,
        code: sourceCode,
        type: options.type,
      };

      return await transformJSON(jsonFile, context);
    }

    if (options.type === 'asset') {
      const file: AssetFile = {
        filename,
        inputFileSize: data.length,
        code: sourceCode,
        type: options.type,
      };

      return await transformAsset(file, context);
    }

    const file: JSFile = {
      filename,
      inputFileSize: data.length,
      code: sourceCode,
      type: options.type === 'script' ? 'js/script' : 'js/module',
      functionMap: null,
    };

    return await transformJSWithBabel(file, context);
  },