Motivation

Experiment with rollup. in particular create one file from few and also exclude.

Setup

According to the official docs it is recommended to install rollup globally

npm install --global rollup

build script

The following take all the files that main.js depend on and create using CommonJS module ('cjs') format a single file - dist/bundle.js ready to run for node application

"build": "rollup src/main.js -o dist/bundle.js -f cjs ",

start script

"start": "node dist/bundle.js"

build with rollup.config.js

some time using config file is easier

export default {
	input: 'src/main.js',
	output: {
		file: 'dist/bundle.js',
		format: 'cjs'
	}
};

and to invoke it simple use

   npm run build-with-config

remark - this is working is you add the following to package.json

  "type": "module",

using dynamic import

some time you do not want one bundle file instead you want code split. this can be done using dynamic import from side e.g.

const { mul } = await import("./utils-b.js");

and on the other side . es is used because the format cjs can not handle it

    "build1": "rollup src/main-with-dynamic-import.js -d dist1 -f es ",

the result is dist1 directory with two files : main-with-dynamic-import.js and utils-b-281616f2.js

watch mode : -w

this will re-bundle on changes

"build-with-config-watch": "rollup -c -w",

invoke main.js without bundle

this is possible provided you will import using .js i.e. import {sum} from './utils.js' not import {sum} from './utils'

and add the following to package.json

  "type": "module",

than invoke

npm run dev

Using import for npm package

add in rollup.config.js

	external: ['dayjs']

note that this will NOT change dist directory . dayjs will be used fron regular node_modules directory. This may be good for development but not production