webpack的使用

package.json中的配置

{
  "name": "code2",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "devDependencies": {
    "@babel/core": "^7.5.0",
    "@babel/preset-env": "^7.5.0",
    "babel-loader": "^8.0.6",
    "css-loader": "^3.0.0",
    "file-loader": "^4.0.0",
    "html-webpack-plugin": "^3.2.0",
    "jquery": "^3.4.1",
    "less": "^3.9.0",
    "less-loader": "^5.0.0",
    "style-loader": "^0.23.1",
    "url-loader": "^2.0.1",
    "webpack": "^4.35.2",
    "webpack-cli": "^3.3.5",
    "webpack-dev-server": "^3.7.2"
  },
  "scripts": {
    "build": "webpack",
    "dev": "webpack-dev-server"
  }
}

　　webpack.config.js中的配置

const path = require('path')
const htmlWebpackPlugin = require('html-webpack-plugin')
module.exports = {
  entry: './src/main.js',
  output: {
    path: path.join(__dirname, 'dist'),
    filename: 'bundle.js'
  },
  mode: 'development',
  plugins: [
    new htmlWebpackPlugin({
      template: path.join(__dirname, './src/index.html'),
      filename: 'index.html'
    })
  ],
  module: {
    rules: [
      //处理css文件的规则
      //yarn add style-loader css-loader
      {
        test: /.css$/,
        use: ['style-loader', 'css-loader']
      },
      //处理css文件的规则
      //yarn add style-loader css-loader less less-loader -D
      {
        test: /.less$/,
        use: ['style-loader', 'css-loader', 'less-loader']
      },
      //处理图片--用file-loader实现
      //yarn add file-loader -D
      // {
      //   test: /.(gif|png|jpe?g)$/,
      //   use: 'file-loader'
      // },
      //处理图片--用url-loader实现
      //yarn add file-loader url-loader -D
      {
        test: /.(gif|png|jpe?g)$/,
        use: [{
          loader: 'url-loader',
          options: {
            limit: 10 * 1024
          }
        }]
      },
　　　//babel-loader把高版本的语法编译成低版本语法
      {
        test: /.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      }
    ]
  },
　// 自动打包
  devServer: {
    open: true,
    port: 3000,
    hot: true
  }
}