Webpack 4:有条件启用PostCSS插件

Question

我使用一个单独的PostCSS文件将postcss.config.js集成到Webpack中。

我希望在进行生产构建时启用cssnano，并为开发构建禁用它。我该怎么做？

这是我的webpack.config.js

const webpack = require('webpack');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const CleanWebpackPlugin = require('clean-webpack-plugin');
const ManifestPlugin = require('webpack-manifest-plugin');

const path = require('path');

module.exports = (env, argv) =>
{
    //const isProduction = (process.env.WEBPACK_MODE === 'production')
    const isProduction = argv.mode === 'production' || process.env.NODE_ENV === 'production';

    const config = {
        entry: './src/index.js',
        output: {
            path: path.resolve(__dirname, 'dist'),
            filename: '[name].[contenthash].js',
            chunkFilename: '[name].[contenthash].js'
        },
        devtool: 'source-map',
        module: {
            rules: [
                {
                    test: /\.(sa|sc|c)ss$/,
                    use: [
                        // fallback to style-loader in development
                        //process.env.NODE_ENV !== 'production' ? 'style-loader' : MiniCssExtractPlugin.loader,
                        {
                            loader: MiniCssExtractPlugin.loader,
                            options: {
                                sourceMap: true
                            }
                        },
                        //'css-loader?-url',
                        {
                            loader: 'css-loader',
                            options: {
                                minimize: true,
                                sourceMap: true,
                                url: false
                            }
                        },
                        {
                            loader: 'postcss-loader',
                            options: {
                                sourceMap: true
                            }
                        },
                        {
                            loader: 'resolve-url-loader',
                            options: {
                                sourceMap: true,
                                debug: false
                            }
                        },
                        {
                            loader: 'sass-loader',
                            options: {
                                sourceMap: true,
                                outputStyle: 'compressed',
                                sourceMapContents: false
                            }
                        }
                    ]
                }
            ]
        },

        plugins: [
            new CleanWebpackPlugin('dist', {
                watch: true
            }),
            new MiniCssExtractPlugin({
                // Options similar to the same options in webpackOptions.output
                // both options are optional
                filename: isProduction ? "live.[contenthash].css" : "live.css",
                chunkFilename: "[name].[contenthash].css"
            }),
            new ManifestPlugin()
        ]
    }

    return config;
}

这是我的postcss.config.js

module.exports = {
    plugins: [
        require('postcss-import'),
        require('postcss-url'),
        require('autoprefixer'),
        require('cssnano')({
            preset: 'default',
        })
    ]
}

第二，是否推荐单独的postcss.config.js？我看到了一些PostCSS插件是在webpack.config.js中定义的例子，还有一些是在单独的文件中完成的。

Answer 1

在你的postcss.config.js中你可以做检查环境属性

module.exports = ({ env }) => ({
  plugins: [
    require('postcss-import')(),
    require('postcss-url')(),
    require('autoprefixer')(),
    env === 'production' ? require('cssnano')({preset: 'default' })() : false,
  ]
})

Answer 2

选项1.使用webpack合并

使用webpack-合并，您可以基于NODE_ENV创建条件配置，并在执行时将它们合并到一个配置中，优点是不创建代码复制，所有操作都可以在一个文件中完成，唯一的缺点是使用新包。

const ENV = process.env.NODE_ENV

let Config = {

  //Other shared configurations by production and development

  plugins: [
    new webpack.ProgressPlugin(),
    new CopyWebpackPlugin([
      { from: 'public', to: 'public' },
    ])
  ]

}

if (ENV === 'production') {
  Config = merge(Config, {
    plugins: [
      new MiniCssExtractPlugin({
        filename: "public/styles.css"
      }),
      new OptimizeCSSAssetsPlugin({
        cssProcessor: cssnano,
        cssProcessorOptions: {
          parser: safe,
          discardComments: { removeAll: true }
        }
      })
    ],
    mode: 'production'
  })
}

if (ENV === 'development') {
  Config = merge(Config, {
    devtool: 'source-map',
    mode: 'development',
    plugins: [
      new webpack.HotModuleReplacementPlugin(),
      new webpack.NamedModulesPlugin(),
      new StyleLintPlugin(
        {
          emitErrors: false,
          configFile: '.stylelintrc',
          context: 'src',
          files: '**/*.pcss',
        },
      ),
    ]
  })
}

const WebpackConfig = Config

选项2.使用不同的配置

可以创建两个分离的文件webpack.config.prod.js和webpack.config.dev.js，并使用不同的npm脚本调用它们。这个解决方案的问题是代码重复。