An Advent to the esbuild Bundler — SitePoint

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esbuild is a quick bundler that may optimize JavaScript, TypeScript, JSX, and CSS code. This article is going to can help you rise up to hurry with esbuild and display you easy methods to create your personal construct machine with out different dependencies.

How Does esbuild Paintings?

Frameworks similar to Vite have followed esbuild, however you’ll be able to use esbuild as a standalone device on your personal tasks.

esbuild bundles JavaScript code right into a unmarried record in a similar fashion to bundlers similar to Rollup. That is esbuild’s number one serve as, and it resolves modules, stories syntax problems, “tree-shakes” to take away unused purposes, erases logging and debugger statements, minifies code, and offers supply maps.
esbuild bundles CSS code right into a unmarried record. It’s now not a complete replace for pre-processors similar to Sass or PostCSS, however esbuild can maintain partials, syntax problems, nesting, inline asset encoding, supply maps, auto-prefixing, and minification. That can be all you wish to have.
esbuild additionally supplies a neighborhood building server with automated bundling and hot-reloading, so there’s no wish to refresh. It doesn’t have the entire options presented via Browsersync, but it surely’s just right sufficient for many circumstances.

The code under will can help you perceive esbuild ideas so you’ll be able to examine additional configuration alternatives in your tasks.

Why Package?

Bundling code right into a unmarried record provides more than a few advantages. Listed below are a few of them:

you’ll be able to expand smaller, self-contained supply information which might be more straightforward to handle
you’ll be able to lint, prettify, and syntax-check code all over the bundling procedure
the bundler can take away unused purposes — referred to as tree-shaking
you’ll be able to package selection variations of the similar code, and create objectives for older browsers, Node.js, Deno, and so forth
unmarried information load quicker than a couple of information and the browser doesn’t require ES module make stronger
production-level bundling can support efficiency via minifying code and taking away logging and debugging statements

Why Use esbuild?

Not like JavaScript bundlers, esbuild is a compiled Pass executable which implements heavy parallel processing. It’s brief and as much as 100 instances quicker than Rollup, Parcel, or Webpack. It might save weeks of building time over the life of a undertaking.

As well as, esbuild additionally provides:

integrated bundling and compilation for JavaScript, TypeScript, JSX, and CSS
command-line, JavaScript, and Pass configuration APIs
make stronger for ES modules and CommonJS
a neighborhood building server with watch mode and reside reloading
plugins so as to add additional capability
complete documentation and an on-line experimentation device

Why Steer clear of esbuild?

On the time of writing, esbuild has reached edition 0.18. It’s dependable however nonetheless a beta product.

esbuild is continuously up to date and choices might exchange between variations. The documentation recommends you persist with a particular edition. You’ll replace it, however you could wish to migrate your configuration information and delve into new documentation to find breaking adjustments.

Observe additionally that esbuild doesn’t carry out TypeScript sort checking, so that you’ll nonetheless wish to run tsc -noEmit.

Tremendous-quick Get started

If important, create a brand new Node.js undertaking with npm init, then set up esbuild in the community as a building dependency:

npm set up esbuild --save-dev --save-exact

The set up calls for round 9MB. Test it really works via operating this command to peer the put in edition:

./node_modules/.bin/esbuild --version

Or run this command to view CLI assist:

./node_modules/.bin/esbuild --help

Use the CLI API to package an access script (myapp.js) and all its imported modules right into a unmarried record named package.js. esbuild will output a record the usage of the default, browser-targeted, immediately-invoked serve as expression (IIFE) structure:

./node_modules/.bin/esbuild myapp.js --bundle --outfile=package.js

You’ll set up esbuild in different ways in the event you’re now not the usage of Node.js.

Instance Venture

Obtain the instance information and an esbuild configuration from Github. It’s a Node.js undertaking, so set up the one esbuild dependency with:

npm set up

Construct the supply information in src to a construct listing and get started a building server with:

npm get started

Now navigate to localhost:8000 on your browser to view a internet web page appearing a real-time clock. While you replace any CSS record in src/css/ or src/css/partials, esbuild will re-bundle the code and reside reload the types.

Press Ctrl|Cmd + Ctrl|Cmd to prevent the server.

Create a manufacturing construct for deployment the usage of:

npm run construct

Read about the CSS and JavaScript information within the construct listing to peer the minified variations with out supply maps.

Venture Review

The actual-time clock web page is built in a construct listing the usage of supply information from src.

The package deal.json record defines 5 npm scripts. The primary deletes the construct listing:

"blank": "rm -rf ./construct",

Earlier than any bundling happens, an init script runs blank, creates a brand new construct listing and copies:

a static HTML record from src/html/index.html to construct/index.html
static photographs from src/photographs/ to construct/photographs/

"init": "npm run blank && mkdir ./construct && cp ./src/html/* ./construct/ && cp -r ./src/photographs ./construct",

An esbuild.config.js record controls the esbuild bundling procedure the usage of the JavaScript API. That is more straightforward to regulate than passing choices to the CLI API, which will transform unwieldy. An npm package script runs init adopted via node ./esbuild.config.js:

"package": "npm run init && node ./esbuild.config.js",

The remaining two npm scripts run package with both a manufacturing or building parameter handed to ./esbuild.config.js to regulate the construct:

"construct": "npm run package -- manufacturing",
"get started": "npm run package -- building"

When ./esbuild.config.js runs, it determines whether or not it must create minified manufacturing information (the default) or building information with automated updates, supply maps, and a live-reloading server. In each circumstances, esbuild bundles:

the access CSS record src/css/major.css to construct/css/major.css
the access JavaScript record scr/js/major.js to construct/js/major.js

Configuring esbuild

package deal.json has a "sort" of "module" so all .js information can use ES Modules. The esbuild.config.js script imports esbuild and units productionMode to true when bundling for manufacturing or false when bundling for building:

import { argv } from 'node:procedure';
import * as esbuild from 'esbuild';

const
  productionMode = ('building' !== (argv[2] || procedure.env.NODE_ENV)),
  goal = 'chrome100,firefox100,safari15'.break up(',');

console.log(`${ productionMode ? 'manufacturing' : 'building' } construct`);

Package goal

Observe that the goal variable defines an array of browsers and edition numbers to make use of within the configuration. This impacts the bundled output and adjustments the syntax to make stronger particular platforms. As an example, esbuild can:

increase local CSS nesting into complete selectors (nesting would stay if "Chrome115" used to be the one goal)
upload CSS vendor-prefixed houses the place important
polyfill the ?? nullish coalescing operator
take away # from non-public elegance fields

In addition to browsers, you’ll be able to additionally goal node and es variations similar to es2020 and esnext (the most recent JS and CSS options).

JavaScript Bundling

The most straightforward API to create a package:

wait for esbuild.construct({
  entryPoints: ['myapp.js'],
  package: true
  outfile: 'package.js'
});

This replicates the CLI command used above:

./node_modules/.bin/esbuild myapp.js --bundle --outfile=package.js

The instance undertaking makes use of extra complex choices similar to record staring at. This calls for a long-running construct context which units the configuration:


const buildJS = wait for esbuild.context({

  entryPoints: [ './src/js/main.js' ],
  structure: 'esm',
  package: true,
  goal,
  drop: productionMode ? ['debugger', 'console'] : [],
  logLevel: productionMode ? 'error' : 'data',
  minify: productionMode,
  sourcemap: !productionMode && 'related',
  outdir: './construct/js'

});

esbuild provides dozens of configuration choices. Right here’s a rundown of those used right here:

entryPoints defines an array of record access issues for bundling. The instance undertaking has one script at ./src/js/major.js.
structure units the output structure. The instance makes use of esm, however you’ll be able to optionally set iife for older browsers or commonjs for Node.js.
package set to true inlines imported modules into the output record.
goal is the array of goal browsers outlined above.
drop is an array of console and/or debugger statements to take away. On this case, manufacturing builds take away each and building builds retain them.
logLevel defines the logging verbosity. The instance above displays mistakes all over manufacturing builds and extra verbose knowledge messages all over building builds.
minify reduces the code length via taking away feedback and whitespace and renaming variables and purposes the place conceivable. The instance undertaking minifies all over manufacturing builds however prettifies code all over building builds.
sourcemap set to related (in building mode best) generates a related supply map in a .map record so the unique supply record and line is to be had in browser developer equipment. You’ll additionally set inline to incorporate the supply map throughout the bundled record, each to create each, or exterior to generate a .map record with no hyperlink from the bundled JavaScript.
outdir defines the bundled record output listing.

Name the context object’s rebuild() strategy to run the construct as soon as — generally for a manufacturing construct:

wait for buildJS.rebuild();
buildJS.dispose();

Name the context object’s watch() strategy to stay operating and robotically re-build when watched information exchange:

wait for buildJS.watch();

The context object guarantees next builds are processed incrementally and that they reuse paintings from earlier builds to support efficiency.

JavaScript enter and output information

The access src/js/major.js record imports dom.js and time.js modules from the lib sub-folder. It unearths all parts with a category of clock and units their textual content content material to the present time each 2nd:

import * as dom from './lib/dom.js';
import { formatHMS } from './lib/time.js';


const clock = dom.getAll('.clock');

if (clock.duration) {

  console.log('initializing clock');

  setInterval(() => {

    clock.forEach(c => c.textContent = formatHMS());

  }, 1000);

}

dom.js exports two purposes. major.js imports each however best makes use of getAll():




export serve as get(selector, document = record) {
  go back document.querySelector(selector);
}


export serve as getAll(selector, document = record) {
  go back Array.from(document.querySelectorAll(selector));
}

time.js exports two purposes. major.js imports formatHMS(), however that makes use of the opposite purposes within the module:




serve as timePad(n) {
  go back String(n).padStart(2, '0');
}


export serve as formatHM(d = new Date()) {
  go back timePad(d.getHours()) + ':' + timePad(d.getMinutes());
}


export serve as formatHMS(d = new Date()) {
  go back formatHM(d) + ':' + timePad(d.getSeconds());
}

The ensuing building package gets rid of (tree shakes) get() from dom.js however comprises the entire time.js purposes. A supply map could also be generated:


serve as getAll(selector, document = record) {
  go back Array.from(document.querySelectorAll(selector));
}


serve as timePad(n) {
  go back String(n).padStart(2, "0");
}

serve as formatHM(d = new Date()) {
  go back timePad(d.getHours()) + ":" + timePad(d.getMinutes());
}

serve as formatHMS(d = new Date()) {
  go back formatHM(d) + ":" + timePad(d.getSeconds());
}


var clock = getAll(".clock");
if (clock.duration) {
  console.log("initializing clock");
  setInterval(() => {
    clock.forEach((c) => c.textContent = formatHMS());
  }, 1e3);
}

(Observe that esbuild can rewrite let and const to var for correctness and velocity.)

The ensuing manufacturing package minifies the code to 322 characters:

serve as o(t,c=record){go back Array.from(c.querySelectorAll(t))}serve as e(t){go back String(t).padStart(2,"0")}serve as l(t=new Date){go back e(t.getHours())+":"+e(t.getMinutes())}serve as r(t=new Date){go back l(t)+":"+e(t.getSeconds())}var n=o(".clock");n.duration&&setInterval(()=>{n.forEach(t=>t.textContent=r())},1e3);

CSS Bundling

CSS bundling within the instance undertaking makes use of a an identical context object to JavaScript above:


const buildCSS = wait for esbuild.context({

  entryPoints: [ './src/css/main.css' ],
  package: true,
  goal,
  exterior: ['/images/*'],
  loader: {
    '.png': 'record',
    '.jpg': 'record',
    '.svg': 'dataurl'
  },
  logLevel: productionMode ? 'error' : 'data',
  minify: productionMode,
  sourcemap: !productionMode && 'related',
  outdir: './construct/css'

});

It defines an exterior possibility as an array of information and paths to exclude from the construct. Within the instance undertaking, information within the src/photographs/ listing are copied to the construct listing so the HTML, CSS, or JavaScript can reference them immediately. If this used to be now not set, esbuild would reproduction information to the output construct/css/ listing when the usage of them in background-image or an identical houses.

The loader possibility adjustments how esbuild handles an imported record that’s now not referenced as an exterior asset. On this instance:

SVG photographs transform inlined as knowledge URIs
PNG and JPG photographs are copied to the construct/css/ listing and referenced as information

CSS enter and output information

The access src/css/major.css record imports variables.css and parts.css from the partials sub-folder:


@import './partials/variables.css';
@import './partials/parts.css';

variables.css defines default customized houses:


:root {
  --font-body: sans-serif;
  --color-fore: #fff;
  --color-back: #112;
}

parts.css defines all types. Observe:

the physique has a background picture loaded from the exterior photographs listing
the h1 is nested within header
the h1 has a background SVG which will probably be inlined
the objective browsers require no seller prefixes


*, *::prior to, ::after {
  box-sizing: border-box;
  font-weight: commonplace;
  padding: 0;
  margin: 0;
}

physique {
  font-family: var(--font-body);
  coloration: var(--color-fore);
  background: var(--color-back) url(/photographs/internet.png) repeat;
  margin: 1em;
}


header {

  & h1 {
    font-size: 2em;
    padding-left: 1.5em;
    margin: 0.5em 0;
    background: url(../../icons/clock.svg) no-repeat;
  }

}

.clock {
  show: block;
  font-size: 5em;
  text-align: middle;
  font-variant-numeric: tabular-nums;
}

The ensuing building package expands the nested syntax, inlines the SVG, and generates a supply map:


:root {
  --font-body: sans-serif;
  --color-fore: #fff;
  --color-back: #112;
}


*,
*::prior to,
::after {
  box-sizing: border-box;
  font-weight: commonplace;
  padding: 0;
  margin: 0;
}
physique {
  font-family: var(--font-body);
  coloration: var(--color-fore);
  background: var(--color-back) url(/photographs/internet.png) repeat;
  margin: 1em;
}
header h1 {
  font-size: 2em;
  padding-left: 1.5em;
  margin: 0.5em 0;
  background: url('knowledge:picture/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><defs><taste>*{fill:none;stroke:%23fff;stroke-width:1.5;stroke-miterlimit:10}</taste></defs><circle cx="12" cy="12" r="10.5"></circle><circle cx="12" cy="12" r="0.95"></circle><polyline issues="12 4.36 12 12 16.77 16.77"></polyline></svg>') no-repeat;
}
.clock {
  show: block;
  font-size: 5em;
  text-align: middle;
  font-variant-numeric: tabular-nums;
}

The ensuing manufacturing package minifies the code to 764 characters (the SVG is ignored right here):

:root{--font-body: sans-serif;--color-fore: #fff;--color-back: #112}*,*:prior to,:after{box-sizing:border-box;font-weight:400;padding:0;margin:0}physique{font-family:var(--font-body);coloration:var(--color-fore);background:var(--color-back) url(/photographs/internet.png) repeat;margin:1em}header h1{font-size:2em;padding-left:1.5em;margin:.5em 0;background:url('knowledge:picture/svg+xml,<svg...></svg>') no-repeat}.clock{show:block;font-size:5em;text-align:middle;font-variant-numeric:tabular-nums}

Staring at, Rebuilding, and Serving

The rest of the esbuild.config.js script bundles as soon as for manufacturing builds prior to terminating:

if (productionMode) {

  
  wait for buildCSS.rebuild();
  buildCSS.dispose();

  wait for buildJS.rebuild();
  buildJS.dispose();

}

Right through building builds, the script assists in keeping operating, watches for record adjustments, and robotically bundles once more. The buildCSS context launches a building internet server with construct/ as the foundation listing:

else {

  
  wait for buildCSS.watch();
  wait for buildJS.watch();

  
  wait for buildCSS.serve({
    servedir: './construct'
  });

}

Get started the advance construct with:

npm get started

Then navigate to localhost:8000 to view the web page.

Not like Browsersync, you’ll wish to upload your personal code to building pages to reside reload. When adjustments happen, esbuild sends details about the replace by means of a server-sent tournament. The most straightforward possibility is to totally reload the web page when any exchange happens:

new EventSource('/esbuild').addEventListener('exchange', () => location.reload());

The instance undertaking makes use of the CSS context object to create the server. That’s as a result of I wish to manually refresh JavaScript adjustments — and since I couldn’t give you the option for esbuild to ship an tournament for each CSS and JS updates! The HTML web page comprises the next script to switch up to date CSS information with no complete web page refresh (a hot-reload):

<script sort="module">
// esbuild server-sent tournament - reside reload CSS
new EventSource('/esbuild').addEventListener('exchange', e => {

  const { added, got rid of, up to date } = JSON.parse(e.knowledge);

  // reload when CSS information are added or got rid of
  if (added.duration || got rid of.duration) {
    location.reload();
    go back;
  }

  // change up to date CSS information
  Array.from(record.getElementsByTagName('hyperlink')).forEach(hyperlink => {

    const url = new URL(hyperlink.href), trail = url.pathname;

    if (up to date.comprises(trail) && url.host === location.host) {

      const css = hyperlink.cloneNode();
      css.onload = () => hyperlink.take away();
      css.href = `${ trail }?${ +new Date() }`;
      hyperlink.after(css);

    }

  })

});

Observe that esbuild doesn’t lately make stronger JavaScript hot-reloading — now not that I’d accept as true with it anyway!

Abstract

With a little bit configuration, esbuild may well be sufficient to maintain your whole undertaking’s building and manufacturing construct necessities.

There’s a complete set of plugins must you require extra complex capability. Remember those incessantly come with Sass, PostCSS, or an identical construct equipment, in order that they successfully use esbuild as a role runner. You’ll all the time create your personal plugins if you wish to have extra light-weight, customized choices.

I’ve been the usage of esbuild for a yr. The rate is fantastic in comparison to an identical bundlers, and new options seem continuously. The one minor problem is breaking adjustments that incur upkeep.

esbuild doesn’t declare to be a unified, all-in-one construct device, but it surely’s most probably nearer to that purpose than Rome.

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