webpack优化环境配置 - 22.tree shaking


tree shaking：去除无用代码
　　前提：1. 必须使用ES6模块化 2. 开启 production 环境
　　作用: 减少代码体积

在package.json中配置
　　"sideEffects": false 所有代码都没有副作用（都可以进行tree shaking）
　　问题：可能会把css / @babel/polyfill （副作用）文件干掉
　　"sideEffects": ["*.css", "*.less"]

1.文件结构

 

 

 

 

2.代码

 index.css

html,body{
    margin: 0;
    padding: 0;
    height: 100%;
    background-color: skyblue;
}

index.js

import { mul } from './test';
import '../css/index.css';

function sum(...arg) {
  return arg.reduce((p, c) => p + c, 0);
}

// eslint-disable-next-line
console.log(sum(1, 2, 3, 4, 5, 6));

console.log(mul(2, 3));

test.js

export function mul(x, y) {
  return x * y;
}

export function count(x, y) {
  return x - y;
}

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>webpack</title>
</head>
<body>
    <h5>hello catch</h5>
</body>
</html>

webpack.config.js

const {resolve} = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const MiniCssExtractPlugin = require('mini-css-extract-plugin')
const OptimizeCssAssetsWebpackPlugin = require('optimize-css-assets-webpack-plugin')

/*
  tree shaking：去除无用代码
    前提：1. 必须使用ES6模块化  2. 开启 production 环境
    作用: 减少代码体积

    在package.json中配置
      "sideEffects": false 所有代码都没有副作用（都可以进行tree shaking）
        问题：可能会把css / @babel/polyfill （副作用）文件干掉
      "sideEffects": ["*.css", "*.less"]
*/

process.env.NODE_ENV = 'production';

const commonCssLoader = [
    MiniCssExtractPlugin.loader,
    'css-loader',
    {
        loader: "postcss-loader",
        options: {
            ident: "postcss",
            plugins: () => [
                require('postcss-preset-env')()
            ]
        }
    }
]

module.exports = {
    entry: './src/js/index.js',
    output: {
        filename: "js/built.[contenthash:10].js",
        path: resolve(__dirname, "build")
    },
    module: {
        rules: [
            {
                test: /\.js$/,
                exclude: /node_modules/,
                enforce: "pre",
                loader: "eslint-loader",
                options: {
                    fix: true,
                }
            },
            {
                oneOf: [
                    {
                        test: /\.css$/,
                        use: [...commonCssLoader]
                    },
                    {
                        test: /\.less$/,
                        use: [...commonCssLoader, 'less-loader']
                    },
                    {
                        test: /\.js$/,
                        exclude: /node_modules/,
                        loader: "babel-loader",
                        options: {
                            presets: [
                                [
                                    '@babel/preset-env',
                                    {
                                        useBuiltIns: 'usage',
                                        corejs: {
                                            version: 3
                                        },
                                        targets: {
                                            chrome: '60',
                                            firefox: '60',
                                            ie: '9',
                                            safari: '10',
                                            edge: '17'
                                        }
                                    }
                                ]
                            ],
                            cacheDirectory: true
                        }
                    },
                    {
                        test: /\.(jpg|png|gif)$/,
                        loader: 'url-loader',
                        options: {
                            limit: 8 * 1024,
                            name: '[hash:10].[ext]',
                            outputPath: 'imgs',
                            esModule: false
                        }
                    },
                    {
                        test: /\.html$/,
                        loader: 'html-loader'
                    },
                    {
                        exclude: /\.(js|css|less|html|png|jpg|gif)$/,
                        loader: "file-loader",
                        options: {
                            outputPath: "media"
                        }
                    }
                ]
            }
        ]
    },
    plugins: [
        new MiniCssExtractPlugin({
            filename: 'css/built.[contenthash:10].css'
        }),
        new OptimizeCssAssetsWebpackPlugin(),
        new HtmlWebpackPlugin({
            template: "./src/index.html",
            minify: {
                collapseWhitespace: true,
                removeComments: true
            }
        })
    ],
    mode: 'production',
    devtool: 'source-map'
}

package.json

{
  "name": "webpack_code",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@babel/core": "^7.8.4",
    "@babel/polyfill": "^7.12.1",
    "@babel/preset-env": "^7.18.10",
    "add-asset-html-webpack-plugin": "^3.2.2",
    "babel": "^6.23.0",
    "babel-loader": "^8.0.6",
    "core-js": "^3.24.1",
    "css-loader": "^3.4.2",
    "eslint": "^6.8.0",
    "eslint-config-airbnb-base": "^14.0.0",
    "eslint-loader": "^3.0.3",
    "eslint-plugin-import": "^2.20.1",
    "file-loader": "^5.0.2",
    "html-loader": "^0.5.5",
    "html-webpack-plugin": "^3.2.0",
    "less": "^3.11.1",
    "less-loader": "^5.0.0",
    "mini-css-extract-plugin": "^0.9.0",
    "optimize-css-assets-webpack-plugin": "^5.0.3",
    "postcss-loader": "^3.0.0",
    "postcss-preset-env": "^6.7.0",
    "style-loader": "^1.1.3",
    "terser-webpack-plugin": "^2.3.5",
    "thread-loader": "^2.1.3",
    "url-loader": "^3.0.0",
    "webpack": "^4.41.6",
    "webpack-cli": "^3.3.11",
    "webpack-dev-server": "^3.10.3",
    "workbox-webpack-plugin": "^5.0.0"
  },
  "dependencies": {
    "jquery": "^3.6.0"
  },
  "browserslist": {
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ],
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ]
  },
  "eslintConfig": {
    "extends": "airbnb-base",
    "env": {
      "browser": true
    }
  },
  "sideEffects": [
    "*.css",
    ".less"
  ]
}

打包

$ webpack

 

 

 

end~

posted @ 2022-09-08 17:40  Evengod  阅读(314)  评论(0)    收藏  举报