webpack1和webpack2版本的区别

webpack1已结再也不维护了，官方在主推webpack2，原先使用webpack1的用户，想要使用v2，只须要作几个配置小改动便可。

咱们只关注经常使用的配置选项，不经常使用的不作解释。

一、resolve配置

之前你可能这么写

resolve: {
    extensions: ['', '.jsx', '.js', '.json'],
    modulesDirectories: ['node_modules', 'src'],
    alias: {
        actions: __dirname + `/src/actions`,
        components: __dirname + `/src/components`,
        containers: __dirname + `/src/containers`,
        reducers: __dirname + `/src/reducers`,
        store: __dirname + `/src/store`
    }
}

如今你该这么写：取消了空字符串

resolve: {
    extensions: ['.js', '.jsx', '.less', '.scss', '.css'],
    modules: [
      path.resolve(__dirname, 'node_modules'),
      path.join(__dirname, './src')
    ]
  }

二、module配置

之前你可能这么写：module: {

loaders: [{
    test: /\.(js|jsx)$/,
    loaders: ['react-hot', 'babel-loader'],
    exclude: /node_modules/
}, {
    test:   /\.(less|css)$/,
    loader: "style-loader!css-loader!less!postcss-loader"
}, {
    test: /\.(png|jpg|gif|svg)$/,
    loader: 'file?name=[md5:hash:base64:10].[ext]'
}, {
    test: /\.json$/,
    loader: 'json'
}, {
    test: /\.md$/,
    loader: 'file?name=[name].[ext]'
}]

}

如今你该这么写：

a、外层loaders改成rules

b、内层loader改成use

c、全部插件必须加上-loader，再也不容许缩写，因此react-hot不须要再配置。

d、再也不支持使用！链接插件，请使用数组形式。

e、json-loader已经被移除，不须要手动添加，webpack会帮你处理好这些事情。

module: {
      rules: [{
          test: /\.(js|jsx)$/,
          use: ['babel-loader'],
          exclude: /node_modules/,
          include: path.join(__dirname, 'src')
      }, {
          test: /\.(less|css)$/,
          use: ["style-loader", "css-loader", "less-loader", "postcss-loader"]
      }, {
          test: /\.(png|jpg|gif|md)$/,
          use: ['file-loader?limit=10000&name=[md5:hash:base64:10].[ext]']
      }, {
          test: /\.svg(\?v=\d+\.\d+\.\d+)?$/,
          use: ['url-loader?limit=10000&mimetype=image/svg+xml']
      }],
  }
};

三、plugins配置

之前你可能这么写：

new webpack.optimize.OccurenceOrderPlugin(),
new webpack.HotModuleReplacementPlugin(),
new webpack.NoErrorsPlugin(),
new webpack.optimize.UglifyJsPlugin()

如今你该这么写：

a、移除了OccurenceOrderPlugin 和 NoErrorsPlugin

b、更多plugins配置请参考 https://webpack.js.org

new webpack.HotModuleReplacementPlugin(),
new webpack.optimize.UglifyJsPlugin()

==============================================================

以上几个经常使用配置变化的比较明显，没有修改的配置会报错致使webpack没法使用，请注意遵照webpack2规则。

最后贴上一份webpack.config.js基础配置，查看该配置完整项目请点击：react-webpack2

var path = require('path');
var webpack = require('webpack');
var autoprefixer = require('autoprefixer');
var precss = require('precss');

//判断当前运行环境是开发模式仍是生产模式
const nodeEnv = process.env.NODE_ENV || 'development';
const isPro = nodeEnv === 'production';

console.log("当前运行环境：", isPro)

var plugins = []
if (isPro) {
  plugins.push(
      new webpack.optimize.UglifyJsPlugin({
          compress: {
              warnings: false
          }
      }),
      new webpack.DefinePlugin({
          'process.env':{
              'NODE_ENV': JSON.stringify(nodeEnv)
          }
      })
  )
} else {
  plugins.push(
      new webpack.DefinePlugin({
          'process.env':{
              'NODE_ENV': JSON.stringify(nodeEnv)
          },
          BASE_URL: JSON.stringify('http://localhost:9009'),
      }),
      // new webpack.optimize.OccurenceOrderPlugin(),
      new webpack.HotModuleReplacementPlugin()
      // new webpack.NoErrorsPlugin()
  )
}

module.exports = {
  devtool: false,
  entry: {
    app: [
      'webpack-hot-middleware/client?path=http://localhost:3011/__webpack_hmr&reload=true&noInfo=false&quiet=false',
      'babel-polyfill',
      './src/index'
    ]
  },
  output: {
    filename: '[name].js',
    path: path.join(__dirname, 'build'),
    publicPath: 'http://localhost:3011/build/',
    chunkFilename: '[name].js'
  },
  // BASE_URL是全局的api接口访问地址
  plugins,
  // alias是配置全局的路径入口名称，只要涉及到下面配置的文件路径，能够直接用定义的单个字母表示整个路径
  resolve: {
    extensions: ['.js', '.jsx', '.less', '.scss', '.css'],
    modules: [
      path.resolve(__dirname, 'node_modules'),
      path.join(__dirname, './src')
    ]
  },

  module: {
      rules: [{
          test: /\.(js|jsx)$/,
          use: ['babel-loader'],
          exclude: /node_modules/,
          include: path.join(__dirname, 'src')
      }, {
          test: /\.(less|css)$/,
          use: ["style-loader", "css-loader", "less-loader", "postcss-loader"]
      }, {
          test: /\.(png|jpg|gif|md)$/,
          use: ['file-loader?limit=10000&name=[md5:hash:base64:10].[ext]']
      }, {
          test: /\.svg(\?v=\d+\.\d+\.\d+)?$/,
          use: ['url-loader?limit=10000&mimetype=image/svg+xml']
      }],
  }
};