从 Typescript 文件导入时，Javascript 代码在 react-scripts 构建中出现“尝试导入错误：”

Question

Getting an error with react-scripts V2.1.3. We are just migrated to this from V1.x. This all worked well previous to the react-scripts upgrade.

The source file (metadataAccess, doing the export) is typescript and has the following code:

export const NAVIGATION = 'Navigation';

The file referencing the const is Javascript as follows:

import { WIDGET_TREE, NAVIGATION, metadataScan } from './universal/metadataAccess';
...
const scanNavigation = await metadataScan(dynamoClient, NAVIGATION);

The error is:

Creating an optimized production build...
Failed to compile.

./src/App.jsx
Attempted import error: 'NAVIGATION' is not exported from './universal/metadataAccess'.

If I were to fix this error (above), I get the same problem on another const. Sadly, the errors are reported one at a time. I also get it on an exported enum. All from Typescript files. I changed the extensions of the referencing files to be .tsx (from .jsx) and it makes no difference.

I have searched the source code of the Typescript compile, webpack, and babel for the string "Attempted import" and not found anything, so I don't even know which code is causing this error.

I also tried adding ".js" to the file name in the import statement, and the (generated) Javascript file has this line:

exports.NAVIGATION = 'Navigation';

It gets the same result. I tried changing the import statement to refer to a non-existent file, and I get a different error, so it seems to be finding the imported file.

Any ideas about how to get this to run?

Answer 1

Below is for react-native-web, and include the solution of "Attempted import error", maybe also helpful for you.

npm install --save-dev react-app-rewired

Create a config-overrides.js in your project root

// used by react-app-rewired

const webpack = require('webpack');
const path = require('path');

module.exports = {
  webpack: function (config, env) {
    config.module.rules[1].use[0].options.baseConfig.extends = [
      path.resolve('.eslintrc.js'),
    ];

    // To let alias like 'react-native/Libraries/Components/StaticRenderer'
    // take effect, must set it before alias 'react-native'
    delete config.resolve.alias['react-native'];
    config.resolve.alias['react-native/Libraries/Components/StaticRenderer'] =
      'react-native-web/dist/vendor/react-native/StaticRenderer';
    config.resolve.alias['react-native'] = path.resolve(
      'web/aliases/react-native',
    );

    // Let's force our code to bundle using the same bundler react native does.
    config.plugins.push(
      new webpack.DefinePlugin({
        __DEV__: env === 'development',
      }),
    );

    // Need this rule to prevent `Attempted import error: 'SOME' is not exported from` when `react-app-rewired build`
    // Need this rule to prevent `TypeError: Cannot assign to read only property 'exports' of object` when `react-app-rewired start`
    config.module.rules.push({
      test: /\.(js|tsx?)$/,
      // You can exclude the exclude property if you don't want to keep adding individual node_modules
      // just keep an eye on how it effects your build times, for this example it's negligible
      // exclude: /node_modules[/\\](?!@react-navigation|react-native-gesture-handler|react-native-screens)/,
      use: {
        loader: 'babel-loader',
      },
    });

    return config;
  },
  paths: function (paths, env) {
    paths.appIndexJs = path.resolve('index.web.js');
    paths.appSrc = path.resolve('.');
    paths.moduleFileExtensions.push('ios.js');
    return paths;
  },
};

Also create a web/aliases/react-native/index.js

// ref to https://levelup.gitconnected.com/react-native-typescript-and-react-native-web-an-arduous-but-rewarding-journey-8f46090ca56b

import {Text as RNText, Image as RNImage} from 'react-native-web';
// Let's export everything from react-native-web
export * from 'react-native-web';

// And let's stub out everything that's missing!
export const ViewPropTypes = {
  style: () => {},
};
RNText.propTypes = {
  style: () => {},
};
RNImage.propTypes = {
  style: () => {},
  source: () => {},
};

export const Text = RNText;
export const Image = RNImage;
// export const ToolbarAndroid = {};
export const requireNativeComponent = () => {};

Now you can just run react-app-rewired start instead of react-scripts start