esbuild-0-28-0 - SKILL.md Agent Skill

name: esbuild-0-28-0 description: Complete toolkit for esbuild v0.28 JavaScript bundler providing CLI, JavaScript API, and Go API access for bundling, minification, transformation, and development workflows with support for TypeScript, JSX, CSS modules, tree shaking, source maps, watch mode, and local development server without requiring npm installation via npx execution. Use when bundling JavaScript/TypeScript projects, configuring build pipelines, setting up watch mode for development, or transforming code without npm dependencies.

esbuild v0.28

Overview

esbuild is an extremely fast JavaScript bundler written in Go that compiles to native code. It bundles ESM and CommonJS modules, transforms TypeScript and JSX to JavaScript, minifies output, generates source maps, and supports CSS bundling including CSS modules. It provides three APIs: CLI, JavaScript (Node.js), and Go — all sharing the same concepts and parameters.

esbuild is 10-100x faster than other bundlers (webpack, rollup, parcel) because it uses parallelism across all CPU cores, writes everything from scratch without third-party dependencies, and touches the AST only three times during compilation. It does not perform type checking — run tsc --noEmit separately for that.

When to Use

Bundling JavaScript/TypeScript/JSX projects for browser or Node.js
Transforming TypeScript to JavaScript without type-checking overhead
Minifying production bundles with source map generation
Setting up fast development workflows with watch mode and local serve
Building CLI tools or libraries that need programmatic bundling via JS or Go API
Converting modern JavaScript syntax for older browser targets
Bundling CSS including @import resolution and CSS modules

Installation / Setup

Via npm (recommended)

npm install --save-exact --save-dev esbuild

Run from node_modules/.bin:

./node_modules/.bin/esbuild --version

Via npx (no install needed)

npx esbuild@0.28.0 --version

Direct binary download (Unix)

curl -fsSL https://esbuild.github.io/dl/v0.28.0 | sh

Or download directly from npm registry without npm installed:

curl -O https://registry.npmjs.org/@esbuild/linux-x64/-/linux-x64-0.28.0.tgz
tar xzf ./linux-x64-0.28.0.tgz
./package/bin/esbuild

Build from source

Requires Go compiler:

git clone --depth 1 --branch v0.28.0 https://github.com/evanw/esbuild.git
cd esbuild
go build ./cmd/esbuild

Cross-compile for other platforms:

GOOS=linux GOARCH=386 go build ./cmd/esbuild

Deno support

import * as esbuild from 'https://deno.land/x/esbuild@v0.28.0/mod.js'
let result = await esbuild.transform('let x: number = 1', { loader: 'ts' })
console.log(result)
await esbuild.stop()

WebAssembly version (unsupported platforms / browser)

npm install --save-exact esbuild-wasm

Note: WASM is ~10x slower than native. Use only when native binary is not available.

Usage Examples

Basic bundling

npx esbuild app.ts --bundle --outfile=dist/bundle.js

Production build with minification and source maps

npx esbuild app.jsx --bundle --minify --sourcemap --target=chrome58,firefox57,safari11,edge16 --outfile=dist/bundle.js

Bundling for Node.js

npx esbuild app.js --bundle --platform=node --target=node18 --outfile=dist/bundle.js

Watch mode

npx esbuild app.ts --bundle --outdir=dist --watch

Local development server

npx esbuild app.ts --bundle --outdir=dist --serve
# Serves at http://127.0.0.1:8000/

JavaScript API

import * as esbuild from 'esbuild'

await esbuild.build({
  entryPoints: ['src/index.ts'],
  bundle: true,
  minify: true,
  sourcemap: true,
  target: ['chrome90', 'firefox90'],
  outdir: 'dist',
})

Transform API (single file, no bundling)

import * as esbuild from 'esbuild'

let result = await esbuild.transform('let x: number = 1', {
  loader: 'ts',
})
console.log(result.code) // "let x = 1;\n"

CSS bundling

npx esbuild --bundle app.css --outfile=dist/bundle.css

Advanced Topics

CLI Reference: Flags, forms, and command-line usage patterns → CLI Reference

JavaScript API: Async/sync APIs, build context, watch/serve/rebuild modes → JavaScript API

Go API: Package structure, BuildOptions, TransformOptions, and incremental builds → Go API

Build Options Reference: Complete documentation of all build and transform options organized by category → Build Options

Content Types and Loaders: JavaScript, TypeScript, JSX, JSON, CSS, text, binary, base64, data URL, external file, empty file → Content Types

Plugin System: onResolve, onLoad, onStart, onEnd, onDispose callbacks with namespaces and filters → Plugin System

Incremental Builds and Live Reload: Watch mode, serve mode, rebuild API, live reload via SSE, CSS hot-reload → Incremental Builds