webpack4+react项目搭建(一)

webpack配置

1.初始化项目

npm init

安装webpack

npm install webpack

2.创建配置目录结构

build---webpack配置
webpack.common.js webpack基础配置
webpack.dev.js webpack开发配置
webpack.prod.js webpack生产配置
config---项目环境配置
scripts---node脚本文件
build.js 生产环境使用脚本
start.js 开发环境使用脚本
src---资源目录

3.先尝试一个简单配置

1）配置启动脚本命令

package.json
scripts: {
  "start": "node ./scripts/start.js", 
  "build": "node ./scripts/build.js"
}

2）编写webpack配置

build/webpack.common.js
const path = require('path');
module.exports = {
  entry: "./src/index.js",
  output: {
    path: path.resolve(__dirname, "../dist"),
    filename: "bundle.js"
  }
}

3）编写开发模式运行脚本

scripts/build.js
 
const webpack = require('webpack'); 
const webpackConfig = require('../build/webpack.common.js'); 
webpack(webpackConfig, (err, stats) => { 
    if(err || stats.hasErrors()){ 
     console.log("编译失败"); 
    } 
});

4）在入口编写一点内容

src/index.js
console.log('hello world');

5）执行npm run build 命令，生成打包目录dist
4.配置开发服务器-webpack-dev-server
1）安装dev服务器和合并配置工具

npm install webpack-dev-server webpack-merge -D

2. 改写webpack配置文件，common文件导出一个可传参数的基本配置生成器， prod和dev文件使用webpack-merge将通用配置和各自模式下的配置进行合并导出

build/webpack.common.js
const path = require('path');
function webpackCommonConfigCreator(options) {
  return {
    mode: options.mode,
    entry: "./src/index.js",
    output: {
      filename: "bundle.js",
      path: path.resolve(__dirname, "../dist")
   }
  }
}
module.exports = webpackCommonConfigCreator;

build/webpack.prod.js
const webpackConfigCreator = require('./webpack.common');
const merge = require('webpack-merge');
const config = { };
const options = {
   mode: 'production'
}
module.exports = merge(webpackConfigCreator(options), config)

build/webpack.dev.js
const webpackConfigCreator = require('./webpack.common');
const merge = require('webpack-merge');
const config = { };
const options = {
  mode: 'development'
}
module.exports = merge(webpackConfigCreator(options), config)

scripts/build.js
const webpack = require('webpack');
const webpackConfig = require('../build/webpack.prod.js’);
webpack(webpackConfig, (err, stats) => {
    if (err || stats.hasErrors()) {
      console.log("编译失败");
    }
})

npm run build 输出正常
3）配置webpack-dev-server
build/webpack.dev.js
contentBase选项是server模式下的output, 开启server后，webpack会实时编译代码到内存

const path = require('path');
const config = {
    devServer: {

    }

}
scripts/start.js
const webpack = require('webpack'); 
const webpackDevServer = require('webpack-dev-server'); 
const webpackConfig = require('../build/webpack.dev.js'); 
const compiler = webpack(webpackConfig); 
const options = Object.assign({}, webpackConfig.devServer, { open: true }) 
const server = new webpackDevServer(compiler, options); 
server.listen(3000, '127.0.0.1', () => { 
    console.log('Starting server on http://localhost:8080'); 
})

运行命令npm run start, 浏览器自动弹出窗口