JSTransformer.js

// @flow
import type {JSONObject, EnvMap} from '@parcel/types';
import type {SchemaEntity} from '@parcel/utils';
import type {Diagnostic} from '@parcel/diagnostic';
import SourceMap from '@parcel/source-map';
import {Transformer} from '@parcel/plugin';
import {init, transform} from '../native';
import path from 'path';
import browserslist from 'browserslist';
import semver from 'semver';
import nullthrows from 'nullthrows';
import ThrowableDiagnostic, {encodeJSONKeyComponent} from '@parcel/diagnostic';
import {validateSchema, remapSourceLocation} from '@parcel/utils';
import {isMatch} from 'micromatch';

const JSX_EXTENSIONS = {
  jsx: true,
  tsx: true,
};

const JSX_PRAGMA = {
  react: {
    pragma: 'React.createElement',
    pragmaFrag: 'React.Fragment',
    automatic: '>= 17.0.0',
  },
  preact: {
    pragma: 'h',
    pragmaFrag: 'Fragment',
    automatic: '>= 10.5.0',
  },
  nervjs: {
    pragma: 'Nerv.createElement',
    pragmaFrag: undefined,
    automatic: undefined,
  },
  hyperapp: {
    pragma: 'h',
    pragmaFrag: undefined,
    automatic: undefined,
  },
};

const BROWSER_MAPPING = {
  and_chr: 'chrome',
  and_ff: 'firefox',
  ie_mob: 'ie',
  ios_saf: 'ios',
  op_mob: 'opera',
  and_qq: null,
  and_uc: null,
  baidu: null,
  bb: null,
  kaios: null,
  op_mini: null,
};

// List of browsers to exclude when the esmodule target is specified.
// Based on https://caniuse.com/#feat=es6-module
const ESMODULE_BROWSERS = [
  'not ie <= 11',
  'not edge < 16',
  'not firefox < 60',
  'not chrome < 61',
  'not safari < 11',
  'not opera < 48',
  'not ios_saf < 11',
  'not op_mini all',
  'not android < 76',
  'not blackberry > 0',
  'not op_mob > 0',
  'not and_chr < 76',
  'not and_ff < 68',
  'not ie_mob > 0',
  'not and_uc > 0',
  'not samsung < 8.2',
  'not and_qq > 0',
  'not baidu > 0',
  'not kaios > 0',
];

const CONFIG_SCHEMA: SchemaEntity = {
  type: 'object',
  properties: {
    inlineFS: {
      type: 'boolean',
    },
    inlineEnvironment: {
      oneOf: [
        {
          type: 'boolean',
        },
        {
          type: 'array',
          items: {
            type: 'string',
          },
        },
      ],
    },
  },
  additionalProperties: false,
};

type PackageJSONConfig = {|
  '@parcel/transformer-js'?: {|
    inlineFS?: boolean,
    inlineEnvironment?: boolean | Array<string>,
  |},
|};

const SCRIPT_ERRORS = {
  browser: {
    message: 'Browser scripts cannot have imports or exports.',
    hint: 'Add the type="module" attribute to the <script> tag.',
  },
  'web-worker': {
    message:
      'Web workers cannot have imports or exports without the `type: "module"` option.',
    hint: "Add {type: 'module'} as a second argument to the Worker constructor.",
  },
  'service-worker': {
    message:
      'Service workers cannot have imports or exports without the `type: "module"` option.',
    hint: "Add {type: 'module'} as a second argument to the navigator.serviceWorker.register() call.",
  },
};

function convertAliasReactIntoPragma(
  alias: string | {|[string]: string|},
): 'react' | 'preact' | 'hyperapp' | 'nervjs' {
  if (typeof alias === 'string') {
    switch (alias) {
      case 'react': {
        return 'react';
      }
      case 'preact/compat':
      case 'preact': {
        return 'preact';
      }
      case 'hyperapp': {
        return 'hyperapp';
      }
      case 'nervjs': {
        return 'nervjs';
      }
      default: {
        return 'react';
      }
    }
  } else {
    for (const key in alias) {
      return convertAliasReactIntoPragma(alias[key]);
    }
  }

  return 'react';
}

type TSConfig = {
  compilerOptions?: {
    // https://www.typescriptlang.org/tsconfig#jsx
    jsx?: 'react' | 'react-jsx' | 'react-jsxdev' | 'preserve' | 'react-native',
    // https://www.typescriptlang.org/tsconfig#jsxFactory
    jsxFactory?: string,
    // https://www.typescriptlang.org/tsconfig#jsxFragmentFactory
    jsxFragmentFactory?: string,
    // https://www.typescriptlang.org/tsconfig#jsxImportSource
    jsxImportSource?: string,
    // https://www.typescriptlang.org/tsconfig#experimentalDecorators
    experimentalDecorators?: boolean,
    ...
  },
  ...
};

export default (new Transformer({
  async loadConfig({config, options}) {
    let pkg = await config.getPackage();
    let isJSX,
      pragma,
      pragmaFrag,
      jsxImportSource,
      automaticJSXRuntime,
      reactRefresh,
      decorators;
    if (config.isSource) {
      let reactLib;
      if (pkg?.alias && pkg.alias['react']) {
        // e.g.: `{ alias: { "react": "preact/compat" } }`
        reactLib = convertAliasReactIntoPragma(pkg.alias['react']);
      } else {
        // Find a dependency that we can map to a JSX pragma
        reactLib = Object.keys(JSX_PRAGMA).find(
          libName =>
            pkg?.dependencies?.[libName] ||
            pkg?.devDependencies?.[libName] ||
            pkg?.peerDependencies?.[libName],
        );
      }

      reactRefresh =
        options.hmrOptions &&
        options.mode === 'development' &&
        Boolean(
          pkg?.dependencies?.react ||
            pkg?.devDependencies?.react ||
            pkg?.peerDependencies?.react,
        );

      let tsconfig = await config.getConfigFrom<TSConfig>(
        options.projectRoot + '/index',
        ['tsconfig.json', 'jsconfig.json'],
      );
      let compilerOptions = tsconfig?.contents?.compilerOptions;

      // Use explicitly defined JSX options in tsconfig.json over inferred values from dependencies.
      pragma =
        compilerOptions?.jsxFactory ||
        (reactLib ? JSX_PRAGMA[reactLib].pragma : undefined);
      pragmaFrag =
        compilerOptions?.jsxFragmentFactory ||
        (reactLib ? JSX_PRAGMA[reactLib].pragmaFrag : undefined);

      if (
        compilerOptions?.jsx === 'react-jsx' ||
        compilerOptions?.jsx === 'react-jsxdev' ||
        compilerOptions?.jsxImportSource
      ) {
        jsxImportSource = compilerOptions?.jsxImportSource;
        automaticJSXRuntime = true;
      } else if (reactLib) {
        let automaticVersion = JSX_PRAGMA[reactLib]?.automatic;
        let reactLibVersion =
          pkg?.dependencies?.[reactLib] ||
          pkg?.devDependencies?.[reactLib] ||
          pkg?.peerDependencies?.[reactLib];
        let minReactLibVersion =
          reactLibVersion != null && reactLibVersion !== '*'
            ? semver.minVersion(reactLibVersion)?.toString()
            : null;

        automaticJSXRuntime =
          automaticVersion &&
          !compilerOptions?.jsxFactory &&
          minReactLibVersion != null &&
          semver.satisfies(minReactLibVersion, automaticVersion);

        if (automaticJSXRuntime) {
          jsxImportSource = reactLib;
        }
      }

      isJSX = Boolean(compilerOptions?.jsx || pragma);
      decorators = compilerOptions?.experimentalDecorators;
    }

    // Check if we should ignore fs calls
    // See https://github.com/defunctzombie/node-browser-resolve#skip
    let ignoreFS =
      pkg &&
      pkg.browser &&
      typeof pkg.browser === 'object' &&
      pkg.browser.fs === false;

    let result = await config.getConfigFrom<PackageJSONConfig>(
      path.join(options.projectRoot, 'index'),
      ['package.json'],
    );
    let rootPkg = result?.contents;

    let inlineEnvironment = config.isSource;
    let inlineFS = !ignoreFS;
    if (result && rootPkg?.['@parcel/transformer-js']) {
      validateSchema.diagnostic(
        CONFIG_SCHEMA,
        {
          data: rootPkg['@parcel/transformer-js'],
          // FIXME
          source: await options.inputFS.readFile(result.filePath, 'utf8'),
          filePath: result.filePath,
          prependKey: `/${encodeJSONKeyComponent('@parcel/transformer-js')}`,
        },
        // FIXME
        '@parcel/transformer-js',
        'Invalid config for @parcel/transformer-js',
      );

      inlineEnvironment =
        rootPkg['@parcel/transformer-js']?.inlineEnvironment ??
        inlineEnvironment;
      inlineFS = rootPkg['@parcel/transformer-js']?.inlineFS ?? inlineFS;
    }

    return {
      isJSX,
      automaticJSXRuntime,
      jsxImportSource,
      pragma,
      pragmaFrag,
      inlineEnvironment,
      inlineFS,
      reactRefresh,
      decorators,
    };
  },
  async transform({asset, config, options, logger}) {
    let [code, originalMap] = await Promise.all([
      asset.getBuffer(),
      asset.getMap(),
      init,
    ]);

    let targets;
    if (asset.isSource) {
      if (asset.env.isElectron() && asset.env.engines.electron) {
        targets = {
          electron: semver.minVersion(asset.env.engines.electron)?.toString(),
        };
      } else if (asset.env.isBrowser() && asset.env.engines.browsers) {
        targets = {};

        let browsers = Array.isArray(asset.env.engines.browsers)
          ? asset.env.engines.browsers
          : [asset.env.engines.browsers];

        // If the output format is esmodule, exclude browsers
        // that support them natively so that we transpile less.
        if (asset.env.outputFormat === 'esmodule') {
          browsers = [...browsers, ...ESMODULE_BROWSERS];
        }

        browsers = browserslist(browsers);
        for (let browser of browsers) {
          let [name, version] = browser.split(' ');
          if (BROWSER_MAPPING.hasOwnProperty(name)) {
            name = BROWSER_MAPPING[name];
            if (!name) {
              continue;
            }
          }

          let [major, minor = '0', patch = '0'] = version
            .split('-')[0]
            .split('.');
          let semverVersion = `${major}.${minor}.${patch}`;

          if (
            targets[name] == null ||
            semver.gt(targets[name], semverVersion)
          ) {
            targets[name] = semverVersion;
          }
        }
      } else if (asset.env.isNode() && asset.env.engines.node) {
        targets = {node: semver.minVersion(asset.env.engines.node)?.toString()};
      }
    }

    let env: EnvMap = {};

    if (!config?.inlineEnvironment) {
      if (options.env.NODE_ENV != null) {
        env.NODE_ENV = options.env.NODE_ENV;
      }

      if (process.env.PARCEL_BUILD_ENV === 'test') {
        env.PARCEL_BUILD_ENV = 'test';
      }
    } else if (Array.isArray(config?.inlineEnvironment)) {
      for (let key in options.env) {
        if (isMatch(key, config.inlineEnvironment)) {
          env[key] = String(options.env[key]);
        }
      }
    } else {
      for (let key in options.env) {
        if (!key.startsWith('npm_')) {
          env[key] = String(options.env[key]);
        }
      }
    }

    let supportsModuleWorkers =
      asset.env.shouldScopeHoist && asset.env.supports('worker-module', true);
    let isJSX = Boolean(config?.isJSX);
    if (asset.isSource) {
      if (asset.type === 'ts') {
        isJSX = false;
      } else if (!isJSX) {
        isJSX = Boolean(JSX_EXTENSIONS[asset.type]);
      }
    }

    let {
      dependencies,
      code: compiledCode,
      map,
      shebang,
      hoist_result,
      symbol_result,
      needs_esm_helpers,
      diagnostics,
      used_env,
    } = transform({
      filename: asset.filePath,
      code,
      module_id: asset.id,
      project_root: options.projectRoot,
      replace_env: !asset.env.isNode(),
      inline_fs: Boolean(config?.inlineFS) && !asset.env.isNode(),
      insert_node_globals: !asset.env.isNode(),
      is_browser: asset.env.isBrowser(),
      is_worker: asset.env.isWorker(),
      env,
      is_type_script: asset.type === 'ts' || asset.type === 'tsx',
      is_jsx: isJSX,
      jsx_pragma: config?.pragma,
      jsx_pragma_frag: config?.pragmaFrag,
      automatic_jsx_runtime: Boolean(config?.automaticJSXRuntime),
      jsx_import_source: config?.jsxImportSource,
      is_development: options.mode === 'development',
      react_refresh:
        asset.env.isBrowser() &&
        !asset.env.isWorker() &&
        !asset.env.isWorklet() &&
        Boolean(config?.reactRefresh),
      decorators: Boolean(config?.decorators),
      targets,
      source_maps: !!asset.env.sourceMap,
      scope_hoist:
        asset.env.shouldScopeHoist && asset.env.sourceType !== 'script',
      source_type: asset.env.sourceType === 'script' ? 'Script' : 'Module',
      supports_module_workers: supportsModuleWorkers,
      is_library: asset.env.isLibrary,
      is_esm_output: asset.env.outputFormat === 'esmodule',
      trace_bailouts: options.logLevel === 'verbose',
    });

    let convertLoc = loc => {
      let location = {
        filePath: asset.filePath,
        start: {
          line: loc.start_line + Number(asset.meta.startLine ?? 1) - 1,
          column: loc.start_col,
        },
        end: {
          line: loc.end_line + Number(asset.meta.startLine ?? 1) - 1,
          column: loc.end_col,
        },
      };

      // If there is an original source map, use it to remap to the original source location.
      if (originalMap) {
        location = remapSourceLocation(location, originalMap);
      }

      return location;
    };

    if (diagnostics) {
      let errors = diagnostics.filter(
        d =>
          d.severity === 'Error' ||
          (d.severity === 'SourceError' && asset.isSource),
      );
      let warnings = diagnostics.filter(
        d =>
          d.severity === 'Warning' ||
          (d.severity === 'SourceError' && !asset.isSource),
      );
      let convertDiagnostic = diagnostic => {
        let message = diagnostic.message;
        if (message === 'SCRIPT_ERROR') {
          let err = SCRIPT_ERRORS[(asset.env.context: string)];
          message = err?.message || SCRIPT_ERRORS.browser.message;
        }

        let res: Diagnostic = {
          message,
          codeFrames: [
            {
              filePath: asset.filePath,
              codeHighlights: diagnostic.code_highlights?.map(highlight => {
                let {start, end} = convertLoc(highlight.loc);
                return {
                  message: highlight.message,
                  start,
                  end,
                };
              }),
            },
          ],
          hints: diagnostic.hints,
        };

        if (diagnostic.documentation_url) {
          res.documentationURL = diagnostic.documentation_url;
        }

        if (diagnostic.show_environment) {
          if (asset.env.loc && asset.env.loc.filePath !== asset.filePath) {
            res.codeFrames?.push({
              filePath: asset.env.loc.filePath,
              codeHighlights: [
                {
                  start: asset.env.loc.start,
                  end: asset.env.loc.end,
                  message: 'The environment was originally created here',
                },
              ],
            });
          }

          let err = SCRIPT_ERRORS[(asset.env.context: string)];
          if (err) {
            if (!res.hints) {
              res.hints = [err.hint];
            } else {
              res.hints.push(err.hint);
            }
          }
        }

        return res;
      };

      if (errors.length > 0) {
        throw new ThrowableDiagnostic({
          diagnostic: errors.map(convertDiagnostic),
        });
      }

      logger.warn(warnings.map(convertDiagnostic));
    }

    if (shebang) {
      asset.meta.interpreter = shebang;
    }

    for (let env of used_env) {
      asset.invalidateOnEnvChange(env);
    }

    for (let dep of dependencies) {
      if (dep.kind === 'WebWorker') {
        // Use native ES module output if the worker was created with `type: 'module'` and all targets
        // support native module workers. Only do this if parent asset output format is also esmodule so that
        // assets can be shared between workers and the main thread in the global output format.
        let outputFormat;
        if (
          asset.env.outputFormat === 'esmodule' &&
          dep.source_type === 'Module' &&
          supportsModuleWorkers
        ) {
          outputFormat = 'esmodule';
        } else {
          outputFormat =
            asset.env.outputFormat === 'commonjs' ? 'commonjs' : 'global';
        }

        let loc = convertLoc(dep.loc);
        asset.addURLDependency(dep.specifier, {
          loc,
          env: {
            context: 'web-worker',
            sourceType: dep.source_type === 'Module' ? 'module' : 'script',
            outputFormat,
            loc,
          },
          meta: {
            webworker: true,
            placeholder: dep.placeholder,
          },
        });
      } else if (dep.kind === 'ServiceWorker') {
        let loc = convertLoc(dep.loc);
        asset.addURLDependency(dep.specifier, {
          loc,
          needsStableName: true,
          env: {
            context: 'service-worker',
            sourceType: dep.source_type === 'Module' ? 'module' : 'script',
            outputFormat: 'global', // TODO: module service worker support
            loc,
          },
          meta: {
            placeholder: dep.placeholder,
          },
        });
      } else if (dep.kind === 'Worklet') {
        let loc = convertLoc(dep.loc);
        asset.addURLDependency(dep.specifier, {
          loc,
          env: {
            context: 'worklet',
            sourceType: 'module',
            outputFormat: 'esmodule', // Worklets require ESM
            loc,
          },
          meta: {
            placeholder: dep.placeholder,
          },
        });
      } else if (dep.kind === 'Url') {
        asset.addURLDependency(dep.specifier, {
          bundleBehavior: 'isolated',
          loc: convertLoc(dep.loc),
          meta: {
            placeholder: dep.placeholder,
          },
        });
      } else if (dep.kind === 'File') {
        asset.invalidateOnFileChange(dep.specifier);
      } else {
        let meta: JSONObject = {kind: dep.kind};
        if (dep.attributes) {
          meta.importAttributes = dep.attributes;
        }

        if (dep.placeholder) {
          meta.placeholder = dep.placeholder;
        }

        let env;
        if (dep.kind === 'DynamicImport') {
          // https://html.spec.whatwg.org/multipage/webappapis.html#hostimportmoduledynamically(referencingscriptormodule,-modulerequest,-promisecapability)
          if (asset.env.isWorklet() || asset.env.context === 'service-worker') {
            let loc = convertLoc(dep.loc);
            let diagnostic = {
              message: `import() is not allowed in ${
                asset.env.isWorklet() ? 'worklets' : 'service workers'
              }.`,
              codeFrames: [
                {
                  filePath: asset.filePath,
                  codeHighlights: [
                    {
                      start: loc.start,
                      end: loc.end,
                    },
                  ],
                },
              ],
              hints: ['Try using a static `import`.'],
            };

            if (asset.env.loc) {
              diagnostic.codeFrames.push({
                filePath: asset.env.loc.filePath,
                codeHighlights: [
                  {
                    start: asset.env.loc.start,
                    end: asset.env.loc.end,
                    message: 'The environment was originally created here',
                  },
                ],
              });
            }

            throw new ThrowableDiagnostic({
              diagnostic,
            });
          }

          // If all of the target engines support dynamic import natively,
          // we can output native ESM if scope hoisting is enabled.
          // Only do this for scripts, rather than modules in the global
          // output format so that assets can be shared between the bundles.
          let outputFormat = asset.env.outputFormat;
          if (
            asset.env.sourceType === 'script' &&
            asset.env.shouldScopeHoist &&
            asset.env.supports('dynamic-import', true)
          ) {
            outputFormat = 'esmodule';
          }

          env = {
            sourceType: 'module',
            outputFormat,
            loc: convertLoc(dep.loc),
          };
        }

        // Always bundle helpers, even with includeNodeModules: false, except if this is a library.
        let isHelper = dep.is_helper && !dep.specifier.endsWith('/jsx-runtime');
        if (isHelper && !asset.env.isLibrary) {
          env = {
            ...env,
            includeNodeModules: true,
          };
        }

        asset.addDependency({
          specifier: dep.specifier,
          specifierType: dep.kind === 'Require' ? 'commonjs' : 'esm',
          loc: convertLoc(dep.loc),
          priority: dep.kind === 'DynamicImport' ? 'lazy' : 'sync',
          isOptional: dep.is_optional,
          meta,
          resolveFrom: isHelper ? __filename : undefined,
          env,
        });
      }
    }

    asset.meta.id = asset.id;
    if (hoist_result) {
      asset.symbols.ensure();
      for (let {exported, local, loc} of hoist_result.exported_symbols) {
        asset.symbols.set(exported, local, convertLoc(loc));
      }

      let deps = new Map(
        asset
          .getDependencies()
          .map(dep => [dep.meta.placeholder ?? dep.specifier, dep]),
      );
      for (let dep of deps.values()) {
        dep.symbols.ensure();
      }

      for (let {
        source,
        local,
        imported,
        loc,
      } of hoist_result.imported_symbols) {
        let dep = deps.get(source);
        if (!dep) continue;
        dep.symbols.set(imported, local, convertLoc(loc));
      }

      for (let {source, local, imported, loc} of hoist_result.re_exports) {
        let dep = deps.get(source);
        if (!dep) continue;

        if (local === '*' && imported === '*') {
          dep.symbols.set('*', '*', convertLoc(loc), true);
        } else {
          let reExportName =
            dep.symbols.get(imported)?.local ??
            `$${asset.id}$re_export$${local}`;
          asset.symbols.set(local, reExportName);
          dep.symbols.set(imported, reExportName, convertLoc(loc), true);
        }
      }

      for (let specifier of hoist_result.wrapped_requires) {
        let dep = deps.get(specifier);
        if (!dep) continue;
        dep.meta.shouldWrap = true;
      }

      for (let name in hoist_result.dynamic_imports) {
        let dep = deps.get(hoist_result.dynamic_imports[name]);
        if (!dep) continue;
        dep.meta.promiseSymbol = name;
      }

      if (hoist_result.self_references.length > 0) {
        let symbols = new Map();
        for (let name of hoist_result.self_references) {
          // Do not create a self-reference for the `default` symbol unless we have seen an __esModule flag.
          if (
            name === 'default' &&
            !asset.symbols.hasExportSymbol('__esModule')
          ) {
            continue;
          }

          let local = nullthrows(asset.symbols.get(name)).local;
          symbols.set(name, {
            local,
            isWeak: false,
            loc: null,
          });
        }

        asset.addDependency({
          specifier: `./${path.basename(asset.filePath)}`,
          specifierType: 'esm',
          symbols,
        });
      }

      // Add * symbol if there are CJS exports, no imports/exports at all, or the asset is wrapped.
      // This allows accessing symbols that don't exist without errors in symbol propagation.
      if (
        hoist_result.has_cjs_exports ||
        (!hoist_result.is_esm &&
          deps.size === 0 &&
          Object.keys(hoist_result.exported_symbols).length === 0) ||
        (hoist_result.should_wrap && !asset.symbols.hasExportSymbol('*'))
      ) {
        asset.symbols.set('*', `$${asset.id}$exports`);
      }

      asset.meta.hasCJSExports = hoist_result.has_cjs_exports;
      asset.meta.staticExports = hoist_result.static_cjs_exports;
      asset.meta.shouldWrap = hoist_result.should_wrap;
    } else {
      if (symbol_result) {
        let deps = new Map(
          asset
            .getDependencies()
            .map(dep => [dep.meta.placeholder ?? dep.specifier, dep]),
        );
        asset.symbols.ensure();

        for (let {exported, local, loc, source} of symbol_result.exports) {
          let dep = source ? deps.get(source) : undefined;
          asset.symbols.set(
            exported,
            `${dep?.id ?? ''}$${local}`,
            convertLoc(loc),
          );
          if (dep != null) {
            dep.symbols.ensure();
            dep.symbols.set(
              local,
              `${dep?.id ?? ''}$${local}`,
              convertLoc(loc),
              true,
            );
          }
        }

        for (let {source, local, imported, loc} of symbol_result.imports) {
          let dep = deps.get(source);
          if (!dep) continue;
          dep.symbols.ensure();
          dep.symbols.set(imported, local, convertLoc(loc));
        }

        for (let {source, loc} of symbol_result.exports_all) {
          let dep = deps.get(source);
          if (!dep) continue;
          dep.symbols.ensure();
          dep.symbols.set('*', '*', convertLoc(loc), true);
        }
      }

      if (needs_esm_helpers) {
        asset.addDependency({
          specifier: '@parcel/transformer-js/src/esmodule-helpers.js',
          specifierType: 'esm',
          resolveFrom: __filename,
          env: {
            includeNodeModules: {
              '@parcel/transformer-js': true,
            },
          },
        });
      }
    }

    asset.type = 'js';
    asset.setBuffer(compiledCode);

    if (map) {
      let sourceMap = new SourceMap(options.projectRoot);
      sourceMap.addVLQMap(JSON.parse(map));
      if (originalMap) {
        sourceMap.extends(originalMap);
      }
      asset.setMap(sourceMap);
    }

    return [asset];
  },
}): Transformer);