文档错误，使用的 webpack-chain v4.9.0 对于 module 的 merge 方法的对象参数只支持 rule 属性，不支持 rules 属性

[Junyan]

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复现步骤

https://nervjs.github.io/taro/docs/config-detail/#miniwebpackchain

// 根据文档
webpackChain(chain, webpack) {
  chain.merge({
    module: {
      rules: {
        myloader: {
          test: /\.md$/,
          use: [{
            loader: 'raw-loader',
            options: {}
          }]
        }
      }
    }
  })

  console.log(chain.toConfig().module);
}

实际结果

mini.webpackChain 中 module 对象使用 rules 属性，无对 .md 文件处理的 loader 配置

{ rules:
   [ { test: /\.sass$/, oneOf: [Array] },
     { test: /\.scss$/, oneOf: [Array] },
     { test: /\.less$/, oneOf: [Array] },
     { test: /\.styl$/, oneOf: [Array] },
     { test: /\.(css|wxss|acss|ttss)(\?.*)?$/, oneOf: [Array] },
     { test: /\.[tj]sx?$/i, include: [Array], use: [Array] },
     { test: /\.(wxml|axml|ttml|qml|swan|jxml)(\?.*)?$/,
       use: [Array] },
     { test: /\.(mp4|webm|ogg|mp3|wav|flac|aac)(\?.*)?$/,
       use: [Array] },
     { test: /\.(woff2?|eot|ttf|otf)(\?.*)?$/, use: [Array] },
     { test: /\.(png|jpe?g|gif|bpm|svg|webp)(\?.*)?$/, use: [Array] } ]
}

期望结果

mini.webpackChain 中 module 对象使用 rule 属性

webpackChain(chain, webpack) {
  chain.merge({
    module: {
      // 由 rules 改成 rule
      rule: {
        myloader: {
          test: /\.md$/,
          use: [{
            loader: 'raw-loader',
            options: {}
          }]
        }
      }
    }
  })

  console.log(chain.toConfig().module);
}

有对 .md 文件处理的 loader 配置

{ rules:
   [ { test: /\.sass$/, oneOf: [Array] },
     { test: /\.scss$/, oneOf: [Array] },
     { test: /\.less$/, oneOf: [Array] },
     { test: /\.styl$/, oneOf: [Array] },
     { test: /\.(css|wxss|acss|ttss)(\?.*)?$/, oneOf: [Array] },
     { test: /\.[tj]sx?$/i, include: [Array], use: [Array] },
     { test: /\.(wxml|axml|ttml|qml|swan|jxml)(\?.*)?$/,
       use: [Array] },
     { test: /\.(mp4|webm|ogg|mp3|wav|flac|aac)(\?.*)?$/,
       use: [Array] },
     { test: /\.(woff2?|eot|ttf|otf)(\?.*)?$/, use: [Array] },
     { test: /\.(png|jpe?g|gif|bpm|svg|webp)(\?.*)?$/, use: [Array] },
     { test: /\.md$/, use: [Array] } ]
}

原因

webpack-chain v4.9.0 文档中 merge 配置可选项：https://www.npmjs.com/package/webpack-chain/v/4.9.0#merging-config
源码：https://github.com/neutrinojs/webpack-chain/blob/v4/src/Config.js

环境信息

👽 Taro v3.0.5


  Taro CLI 3.0.5 environment info:
    System:
      OS: macOS 10.14.4
      Shell: 5.3 - /bin/zsh
    Binaries:
      Node: 10.15.3 - ~/.nvm/versions/node/v10.15.3/bin/node
      Yarn: 1.15.2 - ~/.nvm/versions/node/v10.15.3/bin/yarn
      npm: 6.12.1 - ~/.nvm/versions/node/v10.15.3/bin/npm
    npmPackages:
      @tarojs/cli: 3.0.5 => 3.0.5
      @tarojs/components: 3.0.5 => 3.0.5
      @tarojs/taro: 3.0.5 => 3.0.5
      @tarojs/webpack-runner: 3.0.5 => 3.0.5
      eslint-config-taro: 3.0.5 => 3.0.5
      eslint-plugin-taro: 2.1.4 => 2.1.4
      react: ^16.13.1 => 16.13.1
    npmGlobalPackages:
      typescript: 3.5.3

[Chen-jj]

欢迎 PR~