webpackwebpack-dev-serverpackage.jsonwebpack-4nodemon

The 'mode' option has not been set, webpack will fallback to 'production' for this value.Field 'browser' doesn't contain a valid alias configuration


Project directory structure.

enter image description here

Below are the webpack configuration files.

webpack.config.client.js

const path = require('path');
const webpack = require('webpack');
const CURRENT_WORKING_DIR = process.cwd();

const config = {
  name: 'browser',
  mode: 'development',
  // mode: 'production',
  devtool: 'eval-source-map',
  entry: [
    'webpack-hot-middleware/client?reload=true',
    path.join(CURRENT_WORKING_DIR, 'client/main.js'),
  ],
  output: {
    path: path.join(CURRENT_WORKING_DIR, '/dist'),
    filename: 'bundle.js',
    publicPath: '/dist/',
  },
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        use: ['babel-loader'],
      },
      // To bundle image assets so that other JS code can also access
      // and load it other than the component in which it was imported into.
      {
        test: /\.(ttf|eot|svg|gif|jpg|png)(\?[\s\S]+)?$/,
        use: 'file-loader',
      },
    ],
  },
  plugins: [
    new webpack.HotModuleReplacementPlugin(),
    new webpack.NoEmitOnErrorsPlugin(),
  ],
  resolve: {
    alias: {
      'react-dom': '@hot-loader/react-dom',
    },
  },
};

module.exports = config;

webpack.config.server.js

const path = require('path');
const nodeExternals = require('webpack-node-externals');
const CURRENT_WORKING_DIR = process.cwd();

const config = {
  name: 'server',
  entry: [path.join(CURRENT_WORKING_DIR, './server/server.js')],
  target: 'node',
  output: {
    path: path.join(CURRENT_WORKING_DIR, '/dist/'),
    filename: 'server.generated.js',
    publicPath: '/dist/',
    libraryTarget: 'commonjs2',
  },
  externals: [nodeExternals()],
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: ['babel-loader'],
      },
      // To bundle image assets so that other JS code can also access
      // and load it other than the component in which it was imported into.
      {
        test: /\.(ttf|eot|svg|gif|jpg|png)(\?[\s\S]+)?$/,
        use: 'file-loader',
      },
    ],
  },
};

module.exports = config;

webpack.client.production.js

// const path = require('path');
// const CURRENT_WORKING_DIR = process.cwd();

// const config = {
//   mode: 'production',
//   entry: [path.join(CURRENT_WORKING_DIR, 'client/main.js')],
//   output: {
//     path: path.join(CURRENT_WORKING_DIR, '/dist'),
//     filename: 'bundle.js',
//     publicPath: '/dist/',
//   },
//   module: {
//     rules: [
//       {
//         test: /\.jsx?$/,
//         exclude: /node_modules/,
//         use: ['babel-loader'],
//       },
//       // To bundle image assests so that other JS code can also access
//       // and load it other than the component in which it was imported into.
//       {
//         test: /\.(ttf|eot|svg|gif|jpg|png)(\?[\s\S]+)?$/,
//         use: 'file-loader',
//       },
//     ],
//   },
// };

// module.exports = config;

When I try yarn build , I get the following error.

 WARNING in configuration
    The 'mode' option has not been set, webpack will fallback to 'production' for this value.
    Set 'mode' option to 'development' or 'production' to enable defaults for each environment.
    You can also set it to 'none' to disable any default behavior. Learn more: https://webpack.js.org/configuration/mode/

    ERROR in main
    Module not found: Error: Can't resolve './src' in '/home/prithvi/Desktop/socialize'
    resolve './src' in '/home/prithvi/Desktop/socialize'
      using description file: /home/prithvi/Desktop/socialize/package.json (relative path: .)
        Field 'browser' doesn't contain a valid alias configuration
        using description file: /home/prithvi/Desktop/socialize/package.json (relative path: ./src)
          no extension
            Field 'browser' doesn't contain a valid alias configuration
            /home/prithvi/Desktop/socialize/src doesn't exist
          .js
            Field 'browser' doesn't contain a valid alias configuration
            /home/prithvi/Desktop/socialize/src.js doesn't exist
          .json
            Field 'browser' doesn't contain a valid alias configuration
            /home/prithvi/Desktop/socialize/src.json doesn't exist
          .wasm
            Field 'browser' doesn't contain a valid alias configuration
            /home/prithvi/Desktop/socialize/src.wasm doesn't exist
          as directory
            /home/prithvi/Desktop/socialize/src doesn't exist

    webpack 5.31.0 compiled with 1 error and 1 warning in 256 ms
    error Command failed with exit code 1.

Below are the scripts config & dependencies from package.json file.

"main": "./dist/server.generated.js",
"scripts": {
    "development": "nodemon",
    "build": "webpack --config webpack.config.client.production.js && webpack --mode=production --config webpack.config.server.js",
    "start": "NODE_ENV=production node ./dist/server.generated.js"
},
"dependencies": {
    "@hot-loader/react-dom": "^17.0.1",
    "@material-ui/core": "^4.11.3",
    "@material-ui/icons": "^4.11.2",
    "compression": "^1.7.4",
    "cookie-parser": "^1.4.5",
    "cors": "^2.8.5",
    "express": "^4.17.1",
    "express-jwt": "^6.0.0",
    "helmet": "^4.4.1",
    "jshint": "^2.12.0",
    "jsonwebtoken": "^8.5.1",
    "loadash": "^1.0.0",
    "mongodb": "^3.6.4",
    "mongoose": "^5.12.0",
    "react": "^17.0.2",
    "react-dom": "^17.0.2",
    "react-hot-loader": "^4.13.0",
    "react-router": "^5.2.0",
    "react-router-dom": "^5.2.0"
  },
"devDependencies": {
    "@babel/core": "^7.13.10",
    "@babel/preset-env": "^7.13.10",
    "@babel/preset-react": "^7.13.13",
    "babel-loader": "^8.2.2",
    "file-loader": "^6.2.0",
    "nodemon": "^2.0.7",
    "webpack": "^5.24.4",
    "webpack-cli": "^4.5.0",
    "webpack-dev-middleware": "^4.1.0",
    "webpack-hot-middleware": "^2.25.0",
    "webpack-node-externals": "^2.5.2"
}


Solution

  • enter image description here

    const path = require('path'); // libreria
    module.exports = {
    entry: './js/app.js',
    output: {
        path: path.resolve(__dirname, 'public/js'), 
        filename: 'bundle.js'
    },
    mode: 'development'}
    

    Adding the mode:development command solves the problem.

    enter image description here