前端工程化开发的一个重要标志就是热替换技术，它大大的提高开发效率，使我们专注于写代码，webpack2中的热替换相比较1更加简洁。
1. 先看效果
2.目录结构
3.项目目录结构文件描述
bin 执行文件
node_modules node包
public 静态资源文件
static 静态资源
dist 编译后文件
src 项目js文件
.bablrc babel配置文件
webpack.config.dev.js开发模式webpack配置
webpack.config.pro.js生产模式webpack配置
3.技术依赖
node
react
babel
ES6/ES2015
react-hmre
webpack
babel-loader,css-loader,sass-loader,style-loader,webpack-hot-middleware,webpack-hot-middleware
热加载最重要的几个配置是packge.json/devserver.js/webpack.config.dev.js/webpack.config.prod.js/.babelrc
packge.json
{ "name": "react-hmr-demo", "version": "1.0.0", "description": "react-hmr-demo", "main": "index.js", "scripts": { "dev": "node bin/devserver.js", "build":" webpack --config webpack.config.prod.js ", "start":"node bin/server.js" }, "repository": { "type": "git", "url": "git+https://github.com/leinov/react-hmr-demo.git" }, "author": "leinov", "license": "ISC", "dependencies": { "express": "^4.15.4", "react": "^15.6.1", "react-dom": "^15.6.1" }, "devDependencies": { "babel-core": "^6.26.0", "babel-loader": "^7.1.2", "babel-polyfill": "^6.26.0", "babel-preset-es2015": "^6.24.1", "babel-preset-react": "^6.24.1", "babel-preset-react-hmre": "^1.1.1", "css-loader": "^0.28.5", "eventsource-polyfill": "^0.9.6", "node-sass": "^4.5.3", "sass-loader": "^6.0.6", "style-loader": "^0.18.2", "webpack": "^3.5.5", "webpack-dev-middleware": "^1.12.0", "webpack-hot-middleware": "^2.18.2" } }
scripts的几个命令
$ npm run dev //开发模式 $ npm run build //编译打包 npm start //正式环境运行
webpack.config.dev.js
var path = require('path'); var webpack = require('webpack'); module.exports = { devtool: 'cheap-module-eval-source-map',//打包构建信息 entry: [ 'eventsource-polyfill',//for IE 'webpack-hot-middleware/client',//webpack服务连接到浏览器接收更新 './src/index.js' ], output: { filename: 'boundle.js', publicPath: '/dist/js/' }, module: { loaders: [{ test: /\.js$/, loaders: ['babel-loader'], exclude: /node_modules/ //哪些文件下的需要用到babel }, { test: /\.css$/, loaders: ['style-loader', 'css-loader'], }, { test: /\.scss$/, loaders: ['style-loader', 'css-loader', 'sass-loader'], }, { test: /\.(png|jpg|gif)$/, loaders: ['url?limit=8192&name=images/[name].[ext]'], } ] } , resolve:{ alias: { css: path.resolve(__dirname, 'public/static/css/'), //css目录别名 } }, plugins: [ new webpack.HotModuleReplacementPlugin(),//热替换插件 new webpack.NoEmitOnErrorsPlugin() ] };
.babelrc
{ "presets": ["react", "es2015"]， "env": { "development": { "presets": ["react-hmre"] } } }
devserver.js
var path = require('path'); var express = require('express'); var webpack = require('webpack'); var config = require('../webpack.config.dev'); var app = express(); var compiler = webpack(config); var webpackDevMiddleware = require("webpack-dev-middleware"); app.use(webpackDevMiddleware(compiler, { noInfo: false, //true将打印编译信息（建议false，true会打印很多信息） publicPath: config.output.publicPath //绑定middleware })); var webpackHotMiddleware = require('webpack-hot-middleware'); app.use(webpackHotMiddleware(compiler)); app.get('*', function(req, res) { res.sendFile(path.resolve(__dirname, '../index.html')); // }); app.listen(3100, function(err) { if (err) { console.log(err); return; } console.log('Listening at :3100'); });
这样就可以实现热加载了，在项目根目录执行
$ npm run dev
webpack.config.prod.js
var path = require('path'); var webpack = require('webpack'); module.exports = { devtool: 'cheap-module-eval-source-map', entry: [ './src/index.js' ], output: { path: path.join(__dirname, 'public/dist/js'), filename: 'boundle.js', }, module: { loaders: [{ test: /\.js$/, loaders: ['babel-loader'], exclude: /node_modules/ }, { test: /\.css$/, loaders: ['style-loader', 'css-loader'], }, { test: /\.scss$/, loaders: ['style-loader', 'css-loader', 'sass-loader'], }, { test: /\.(png|jpg|gif)$/, loaders: ['url?limit=8192&name=images/[name].[ext]'], } ] } , resolve:{ alias: { css: path.resolve(__dirname, 'public/static/css/'), img: path.resolve(__dirname, 'public/static/img/'), } }, plugins: [ new webpack.HotModuleReplacementPlugin(), new webpack.NoEmitOnErrorsPlugin(), new webpack.optimize.UglifyJsPlugin({ compress: { warnings: false } }) ] };
生产的webpack主要完成开发后的编译打包，在plugins里多了压缩插件,在项目根目录执行
$ npm run build
bin/server.js
生产环境启动文件