webpack4 配置 ssr 环境遇到“document is not defined”

最近使用 webpack 4 配置 ssr 环境，发现的问题：

ReferenceError: document is not defined

本次package.json使用版本信息：

{ "vue-loader": "^15.4.2", "mini-css-extract-plugin": "^0.4.3", "webpack": "^4.20.2", "webpack-cli": "^3.1.2" ... }

相关代码

问题原因：

在服务端渲染打包的配置中使用了mini-css-extract-plugin是的server bundle中会使用到document，node环境中不存在window对象，所以报错。

解决办法：

在webpack.base.config.js中不配置样式相关的loader：

# 基本配置 const path = require('path') const webpack = require('webpack') const {VueLoaderPlugin} = require('vue-loader') const FriendlyErrorsPlugin = require('friendly-errors-webpack-plugin') const resolve = dir => path.join(__dirname, '../', dir) const isProd = process.env.NODE_ENV === 'production' const base = { mode: isProd ? 'production' : 'development', devtool: isProd ? false : 'cheap-eval-source-map', output: { path: path.resolve(__dirname, '../dist'), publicPath: '/dist/', filename: '[name].[chunkhash].js' }, resolve: { alias: { 'vue$': 'vue/dist/vue.esm.js', 'public': path.resolve(__dirname, '../public') } }, module: { noParse: /es6-promise\.js$/, // avoid webpack shimming process rules: [ { test: /\.vue$/, loader: 'vue-loader', include: resolve("src") }, { test: /\.js$/, loader: 'babel-loader', exclude: file => ( /node_modules/.test(file) && !/\.vue\.js/.test(file) ) }, { test: /\.(png|jpg|gif|svg)$/, loader: 'url-loader', options: { limit: 10000, name: '[name].[ext]?[hash]' } } ] }, plugins: setPlugin() } function setPlugin() { const base = [new VueLoaderPlugin()] const dev = [new FriendlyErrorsPlugin()] const prod = [] return base.concat(isProd ? prod : dev) } module.exports = base;

在webpack.client.config.js中使用mini-css-extract-plugin：

# 只展示先关配置 const webpack = require('webpack') const merge = require('webpack-merge') const base = require('./webpack.base.config') const MiniCssExtractPlugin = require("mini-css-extract-plugin"); const VueSSRClientPlugin = require('vue-server-renderer/client-plugin') const isProd = process.env.NODE_ENV === 'production' const config = merge(base, { module: { rules: [ { test: /\.styl(us)?$/, use: [ isProd ? MiniCssExtractPlugin.loader : 'vue-style-loader', { loader: 'css-loader' }, 'stylus-loader' ], }, { test: /\.(le|c)ss$/, use: [ isProd ? MiniCssExtractPlugin.loader : 'vue-style-loader', { loader: 'css-loader' }, 'less-loader', ], } ] }, plugins: [ new MiniCssExtractPlugin({ filename: isProd ? '[name].[chunkhash].css' : '[name].css', chunkFilename: isProd ? '[id].[chunkhash].css': '[id].css', }), new VueSSRClientPlugin() ] }) module.exports = config

在webpack.server.config.js中不使用mini-css-extract-plugin：

# 只展示先关配置 const webpack = require('webpack') const merge = require('webpack-merge') const base = require('./webpack.base.config') const VueSSRServerPlugin = require('vue-server-renderer/server-plugin') module.exports = merge(base, { target: 'node', module: { rules: [ { test: /\.styl(us)?$/, use: [ 'vue-style-loader', { loader: 'css-loader' }, 'stylus-loader' ], }, { test: /\.(le|c)ss$/, use: [ 'vue-style-loader', { loader: 'css-loader' }, 'less-loader', ], } ] }, plugins: [ new VueSSRServerPlugin() ] })

参考Demo:

tiodot/vnews

相关issues:

vue-loader@15.0.0-rc.1 in a server bundle

结语：

由于本次webpack4版本比较新，周边的插件没能及时做出相应更新；

相信经过社区的不断努力，整个生态会更加健壮。