Webpack

mkdir webpack-demo
cd webpack-demo
pnpm init
pnpm install webpack webpack-cli -D

默认使用production模式打包，默认开启treeshaking
默认打包生成的文件名为main.js

const path = require('path')
module.exports ={
  // webpack打包的基础目录，不设置时默认就是根目录 '.'
  context: path.resolve(__dirname , './src'),
  // 此时打包入口为 './src/app.js'
  entry: './app.js'
}
// entry使用字符串与下面等价
entry: {
  main: './app.js'
}

entry使用数组形式
文件名必须带有路径，'a.js'会被当作npm包去node_modules里解析
Requests that should resolve in the current directory need to start with ‘./‘.
Requests that start with a name are treated as module requests and resolve within module directories (node_modules).
If changing the source code is not an option there is also a resolve options called ‘preferRelative’ which tries to resolve these kind of requests in the current directory too.

const path = require('path')
module.exports = {
  context: path.resolve(__dirname, './src'),
  entry: ['./a.js', './b.js', './app.js']
}

上面数组形式仍然只会生成一个文件main.js，以app.js为入口，前两个文件为依赖，相当于

// app.js
import a from './a.js'
import b from './b.js'
// app的代码
...