1. npm init 创建文件夹，初始化npm 环境
2. 安装各种包 npm install webpack webpack-dev-server style-loader css-loader url-loader babel-loader sass-loader file-loader
3. 创建webpack.config.js

var path =require("path");
module.exports = {
    entry: path.join(__dirname,'./src/entry.js'),output: {
        path: path.join(__dirname,'out'),publicPath: "./out/",filename: 'bundle.js',publicPath: "/assets/"

    },module: {
        loaders: [
            {test: /\.js$/,loader: "babel"},{test: /\.css$/,loader: "style!css"},{test: /\.(jpg|png)$/,loader: "url?limit=8192"},{test: /\.scss$/,loader: "style!css!sass"}
        ]
    }
};

package.json 添加启动脚本

"scripts": {
    "start": "webpack-dev-server --inline --content-base src/"
  }

运行

npm run start
访问
http://localhost:8080/

react dev server 热部署 环境搭建完成

参考文档
http://webpack.github.io/docs/webpack-dev-server.html（官网）