javascript - 引用错误: _ref2 is not defined @ react-dom. production.min.js

Question

我在设置 webpack 构建配置时遇到问题。我有两个 webpack 配置文件，一个用于开发，一个用于生产。

在开发环境中一切正常，但是在构建生产环境时，我收到此错误:

ReferenceError: _ref2 is not defined
    at e.value (App.js:20)
    at c (react-dom.production.min.js:147)
    at beginWork (react-dom.production.min.js:150)
    at i (react-dom.production.min.js:182)
    at c (react-dom.production.min.js:183)
    at l (react-dom.production.min.js:184)
    at v (react-dom.production.min.js:188)
    at h (react-dom.production.min.js:187)
    at Object.updateContainer (react-dom.production.min.js:248)
    at react-dom.production.min.js:254

这是我的 webpack 配置文件:

webpack.config.dev.js

import webpack from 'webpack';
import HtmlWebpackPlugin from 'html-webpack-plugin';
import path from 'path';
// import 'babel-polyfill';

export default {
  resolve: {
    extensions: ['*', '.js', '.jsx', '.json']
  },
  devtool: 'cheap-module-eval-source-map', // more info:https://webpack.js.org/guides/development/#using-source-maps and https://webpack.js.org/configuration/devtool/
  entry: [
    // must be first entry to properly set public path
    'babel-polyfill',
    './src/webpack-public-path',
    'react-hot-loader/patch',
    'webpack-hot-middleware/client?reload=true',
    path.resolve(__dirname, 'src/index.js') // Defining path seems necessary for this to work consistently on Windows machines.
  ],
  target: 'web',
  output: {
    path: path.resolve(__dirname, 'dist'), // Note: Physical files are only output by the production build task `npm run build`.
    publicPath: '/',
    filename: 'bundle.js'
  },
  plugins: [
    new webpack.DefinePlugin({
      'process.env.NODE_ENV': JSON.stringify('development'), // Tells React to build in either dev or prod modes. https://facebook.github.io/react/downloads.html (See bottom)
      __DEV__: true
    }),
    new webpack.HotModuleReplacementPlugin(),
    new webpack.NoEmitOnErrorsPlugin(),
    new HtmlWebpackPlugin({     // Create HTML file that includes references to bundled CSS and JS.
      template: 'src/index.ejs',
      minify: {
        removeComments: true,
        collapseWhitespace: true
      },
      inject: true
    })
  ],
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        use: ['babel-loader']
      },
      {
        test: /\.eot(\?v=\d+.\d+.\d+)?$/,
        use: ['file-loader']
      },
      {
        test: /\.woff(2)?(\?v=[0-9]\.[0-9]\.[0-9])?$/,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 10000,
              mimetype: 'application/font-woff'
            }
          }
        ]
      },
      {
        test: /\.[ot]tf(\?v=\d+.\d+.\d+)?$/,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 10000,
              mimetype: 'application/octet-stream'
            }
          }
        ]
      },
      {
        test: /\.svg(\?v=\d+\.\d+\.\d+)?$/,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 10000,
              mimetype: 'image/svg+xml'
            }
          }
        ]
      },
      {
        test: /\.(jpe?g|png|gif|ico)$/i,
        use: [
          {
            loader: 'file-loader',
            options: {
              name: '[name].[ext]'
            }
          }
        ]
      },
      {
        test: /(\.css|\.scss|\.sass)$/,
        exclude: /node_modules/,
        use: [
          'style-loader',
          {
            loader: 'css-loader',
            options: {
              sourceMap: true
            }
          }, {
            loader: 'postcss-loader',
            options: {
              plugins: () => [
                require('autoprefixer')
              ],
              sourceMap: true
            }
          }, {
            loader: 'sass-loader',
            options: {
              includePaths: [path.resolve(__dirname, 'src', 'scss')],
              sourceMap: true
            }
          }
        ]
      }
    ]
  }
};

webpack.config.prod.js

// For info about this file refer to webpack and webpack-hot-middleware documentation
// For info on how we're generating bundles with hashed filenames for cache busting: https://medium.com/@okonetchnikov/long-term-caching-of-static-assets-with-webpack-1ecb139adb95#.w99i89nsz
import webpack from 'webpack';
import ExtractTextPlugin from 'extract-text-webpack-plugin';
import WebpackMd5Hash from 'webpack-md5-hash';
import HtmlWebpackPlugin from 'html-webpack-plugin';
import path from 'path';

const GLOBALS = {
  'process.env.NODE_ENV': JSON.stringify('production'),
  __DEV__: false
};

export default {
  resolve: {
    extensions: ['*', '.js', '.jsx', '.json']
  },
  devtool: 'source-map', // more info:https://webpack.js.org/guides/production/#source-mapping and https://webpack.js.org/configuration/devtool/
  entry: ['babel-polyfill', './src/webpack-public-path', path.resolve(__dirname, 'src/index.js')],
  target: 'web',
  output: {
    path: path.resolve(__dirname, 'dist'),
    publicPath: '',
    filename: '[name].[chunkhash].js'
  },
  plugins: [
    // Hash the files using MD5 so that their names change when the content changes.
    new WebpackMd5Hash(),

    // Tells React to build in prod mode. https://facebook.github.io/react/downloads.html
    new webpack.DefinePlugin(GLOBALS),

    // Generate an external css file with a hash in the filename
    new ExtractTextPlugin('[name].[contenthash].css'),

    // Generate HTML file that contains references to generated bundles. See here for how this works: https://github.com/ampedandwired/html-webpack-plugin#basic-usage
    new HtmlWebpackPlugin({
      template: 'src/index.ejs',
      favicon: 'src/favicon.ico',
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeRedundantAttributes: true,
        useShortDoctype: true,
        removeEmptyAttributes: true,
        removeStyleLinkTypeAttributes: true,
        keepClosingSlash: true,
        minifyJS: true,
        minifyCSS: true,
        minifyURLs: true
      },
      inject: true
    }),

    // Minify JS
    new webpack.optimize.UglifyJsPlugin({sourceMap: true}),
  ],
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        use: ['babel-loader']
      },
      {
        test: /\.eot(\?v=\d+.\d+.\d+)?$/,
        use: [
          {
            loader: 'url-loader',
            options: {
              name: 'fonts/[name].[contenthash].[ext]'
            }
          }
        ]
      },
      {
        test: /\.woff(2)?(\?v=[0-9]\.[0-9]\.[0-9])?$/,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 10000,
              mimetype: 'application/font-woff',
              name: 'fonts/[name].[contenthash].[ext]'
            }
          }
        ]
      },
      {
        test: /\.[ot]tf(\?v=\d+.\d+.\d+)?$/,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 10000,
              mimetype: 'application/octet-stream',
              name: 'fonts/[name].[contenthash].[ext]'
            }
          }
        ]
      },
      {
        test: /\.svg(\?v=\d+\.\d+\.\d+)?$/,
        use: [
          {
            loader: 'url-loader',
            options: {
              limit: 10000,
              mimetype: 'image/svg+xml',
              name: 'img/[name].[contenthash].[ext]'
            }
          }
        ]
      },
      {
        test: /\.(jpe?g|png|gif)$/i,
        use: [
          {
            loader: 'file-loader',
            options: {
              name: 'img/[name].[contenthash].[ext]'
            }
          }
        ]
      },
      {
        test: /(\.css|\.scss|\.sass)$/,
        exclude: /node_modules/,
        use: ExtractTextPlugin.extract({
          use: [
            {
              loader: 'css-loader',
              options: {
                minimize: true,
                sourceMap: true
              }
            },
            {
              loader: 'postcss-loader',
              options: {
                plugins: () => [
                  require('autoprefixer')
                ],
                sourceMap: true
              }
            },
            {
              loader: 'sass-loader',
              options: {
                includePaths: [path.resolve(__dirname, 'src', 'scss')],
                sourceMap: true
              }
            }
          ]
        })
      }
    ]
  }
};

.babelrc

{
  "presets": [
    "react",
    "stage-1",
    "flow"
  ],
  "env": {
    "development": {
      "presets": [
        "env",
        "react-hmre"
      ],
      "plugins": [
        "transform-regenerator",
        [
          "transform-class-properties",
          {
            "spec": true
          }
        ]
      ]
    },
    "production": {
      "presets": [
        [
          "env",
          {
            "es2015": {
              "modules": false
            },
            "targets": {
              "ie": 9,
              "uglify": true
            }
          }
        ]
      ],
      "plugins": [
        "transform-regenerator",
        "transform-react-constant-elements",
        "transform-react-remove-prop-types",
        [
          "transform-class-properties",
          {
            "spec": true
          }
        ]
      ]
    },
    "test": {
      "presets": [
        "env"
      ],
      "plugins": [
        "transform-regenerator",
        [
          "transform-class-properties",
          {
            "spec": true
          }
        ]
      ]
    }
  }
}

我不知道哪个配置可能导致此错误。

Answer 1

我认为这不是 webpack 的问题，而是 App.js 文件的问题。

就我而言，存在“let”声明问题。它在开发环境中运行，但不在生产环境中运行。基本上，在构建过程中，我们需要特别注意 const/let/function 声明的顺序和范围，以便在构建之后，声明引用将获得实际的声明。

我的案例是:

const products = products.map(group => {
   let resultButton = '';
   if (!group.product[0].soldout) {
    let price = 0;
    price += group.product[0].amount.amount;
    if (group.product[0].fees) {
     for (let i = 0; i < group.product[0].fees.length; i += 1) {
      price += group.product[0].fees[i].amount;
      }
     }

     // here was my wrong declaration
     // I corrected by declaring outside of if (!group.product[0].soldout) 
     // below let resultButton = '';
     // & it works for me after build
     let benefits = <li>No benefits defined</li>;

     if (
     group.product[0].properties&&
        group.product[0].properties.length > 0
      ) {

        _.map(group.product[0].properties.property, property => {
          if (property.code === 51) {
            const benefitsArray = property.content.split('\n');
            benefits = benefitsArray.map(item => {
              const st = item.replace(/ +/g, '');
              return <li key={st}>{item}</li>;
          });
          }
        });
      }
      
      resultButton = (
        <div>
          <h4>
          <ul>{benefits}</ul>
        </div>
      );
    } else {
      resultButton = (
        <div>
          <SoldOut>
        </div>
      );
    }
    return resultButton;
  });

希望您能得到答案。