Using Bundlers

If you don't know why you should use bundlers, read up Why webpack.

There are currently three JavaScript bundlers.

  • webpack
    • By far the most used bundler with a lot of community made extensions
  • rollup
    • Primarily used by libraries like React, Vue
  • parcel
    • New bundler famous for zero-config, and super fast building process

These bundlers allows you to

  • write modular, organised source code
  • treat CSS, images, or any sort of files like JavaScript module
  • use npm packages for front-end (dashboard/graphics)
  • use JSX/TSX, Vue single file component
  • write in other languages like TypeScript
  • and many more

This tutorial goes through the setup using parcel.

Directory Structure

Basically you will have parcel to output the whole dashboard and graphics directory. Your project would look like this

|- extension
|- schemas
|- src
|- package.json

When you run parcel, it will make dashboard and graphics directory and output bundle result into them.

(After running parcel)

|- extension
|- schemas
|- src
|- package.json
|- dashboard (built)
|- index.html
|- styles.8jx17sx.css
|- main.7x2hdjs.js
|- graphics (built)
|- ds1.html
|- sd1.html
|- styles.03nsh2s.css
|- ds1.rssiahs.js
|- sd1.4jc71nx.js
|- background.d8frsis.png

The random string for each generated files are automatically generated to refresh cache when the files change.


As I said, parcel is (literally) zero-configuration required. It even installs missing packages for you if there is any.

Add parcel to your bundle


npm install --save-dev parcel-bundler
# or
yarn add -D parcel-bundler

The parcel command will be available locally. You can run it either adding npm scripts, or npx parcel/yarn parcel.


npm install -g parcel-bundler
# or
yarn global add parcel-bundler

With this, parcel command should be available globally. Just run parcel to run the bundler.

Make an entrypoint

When building front-end, HTML file is usually used as entrypoint. You can just use your HTML file with your scripts and stylesheets imported.

<!DOCTYPE html>
<meta charset="utf-8" />
<link rel="stylesheet" href="./styles.css">
<div id="tech"></div>
<!-- Or a lot of pre-defined elements -->
<script src="./index.js"></script>

The entrypoint HTML file will also be compiled in the bundler. So you can have many kind of files in the script tag. Parcel will automatically detect file format and use an appropriate library/compiler to bundle the file.

<script src="./"></script>
<script src="./app.tsx"></script>

Or the entrypoint doesn't even have to be an HTML file. For example, you can use Pug to have common parts of HTML file into one file.

doctype html
title graphics-ds
include lib/common.pug

Run the command

For development, with file change detection and hot-reloading:

parcel watch src/dashboard/index.html --out-dir dashboard --public-url ./

For production build, with optimized output:

parcel build src/dashboard/index.html --out-dir dashboard --public-url ./

(Replace src/dashboard/index.html with your entrypoint files.)

You can use a glob pattern to use multiple entrypoints, if you have multiple pages to compile

parcel build src/dashboard/*.html --out-dir dashboard --public-url ./

Details described in the reference.

Recommended Configuration

Even though it already works for most cases (!), a bit of configuration might be recommended/required.


Parcel uses babel out of box, and the default supported browsers are >0.25% which includes old browsers like IE.

Considering how NodeCG is used, it's the best to target only modern browsers or just Chrome. To do so, add browserslist property to package.json.

For example,

// ...
"browserslist": "last 2 chrome versions",
"nodecg": //...

Refer to this page for detailed browserslist syntax.

Going further

Due to the huge amount of features parcel offers out of box, at this point you already have a lot more options for your front-end development. For example:

  • React development with JSX/TSX
  • Vue single file component
  • TypeScript or other alternative languages

Also, if your project becomes too advanced for parcel to handle, you can switch to webpack. It produces a bit more optimized code, and has a lot more features supported.

Last updated on by zoton2