引言
项目中经常用到共用的js，这里就需要用到共用js打包，这篇文章讲解两种打包方式，webpack打包和rollup打包两种方式

1、webpack打包js

1.1 在根目录创建 webpack.config.js，配置如下

const path = require('path');
module.exports = {entry: './index.js', output:{filename:'index.js',path:path.resolve(__dirname,'dist'),library: 'myModule',libraryTarget:'umd'},// 以下代码为新添加代码module:{rules:[{test: /\.js$/, // 匹配所有 js 文件loader: 'babel-loader' // 使用 babel-loader 处理 js 文件},]},
};

1.2 安装依赖包 package.json

npm install @babel/core @babel/preset-env babel-loader @babel/plugin-transform-runtime 这里用来将es6转成es5
npm install webpack webpack-cli

{"main": "index.js","scripts": {"buildwebpack": "webpack"},"devDependencies": {"@babel/core": "^7.23.9","@babel/preset-env": "^7.23.9","babel-loader": "^9.1.3","webpack": "^5.90.0","webpack-cli": "^5.1.4"},"dependencies": {"@babel/plugin-transform-runtime": "^7.23.9"}
}

1.3 配置 babel.config.js

const presets = [["@babel/env",{targets: {ie: "6",edge: "17",firefox: "60",chrome: "67",safari: "11.1"},//useBuiltIns: "usage",//corejs: "3", // <---  此处加个这个，就没有报错警告了},],
];module.exports = { presets,"plugins": ["@babel/transform-runtime"]
};

1.4 webpack 支持vue

“vue-loader”: “^15.11.1”,
“vue-template-compiler”: “^2.6.12” //需要和vue版本一致
npm install vue-loader@15 vue-template-compiler@2 vue@2 css-loader

const path = require('path');
const {VueLoaderPlugin} = require('vue-loader')
module.exports = {entry: './index.js', output:{filename:'index.js',path:path.resolve(__dirname,'dist'),library: 'myModule',libraryTarget:'umd'},// 以下代码为新添加代码module:{rules:[{test: /\.js$/, // 匹配所有 js 文件loader: 'babel-loader' // 使用 babel-loader 处理 js 文件},{test: /\.vue$/, loader: 'vue-loader'},
//    { test: /\.css$/, 
//      use: ['style-loader','css-loader' ]
//    },]},//需要注意的点：vue-loader 15版本需加入插件plugins: [new VueLoaderPlugin()]
};

2、rollup 打包js

2.1 在根目录创建 rollup.config.js，配置如下

import babel from 'rollup-plugin-babel';
export default {input: 'index.js',output: {file: 'lib/index.js',format: 'cjs',},plugins: [ babel({runtimeHelpers: true, presets: ["@babel/preset-env"],}) ],
};

2.2 安装依赖包 package.json

npm install @babel/core @babel/preset-env 这里用来将es6转成es5
npm install rollup rollup-plugin-babel

{"main": "index.js","scripts": {"buildrollup": "rollup -c",},"devDependencies": {"@babel/core": "^7.23.9","@babel/preset-env": "^7.23.9","babel-loader": "^9.1.3"},"dependencies": {"@babel/plugin-transform-runtime": "^7.23.9","rollup": "^2.79.1","rollup-plugin-babel": "^4.4.0"}
}

2.4 rollup 打包vue

rollup-plugin-vue^5.1.9 + vue-template-compiler
rollup-plugin-postcss 识别css和预处理文件
npm install rollup-plugin-vue@5 vue-template-compiler rollup-plugin-postcss

export default {input: 'index.js',output: {file: 'lib/index.js',format: 'cjs',},plugins: [ babel({runtimeHelpers: true, presets: ["@babel/preset-env"],}),vue2({css:true,compilerTemplate: true,preprocessStyles: true}) ],
};