Bun for Beginners

What this book is, the four pillars of Bun, and how the chapters fit together.

Install Bun on macOS, Linux, or Windows. Get Git working. Confirm everything runs before we write a line of code.

Scaffold a project with bun init, write a server with Bun.serve, return HTML, add routes, and run it all in watch mode.

Build a command-line word counter. Read arguments and files with Bun's built-in APIs. Install your first package with bun add.

Extract countWords into its own file, write tests with bun:test, and use watch mode to get instant feedback as you code.

Add multiple routes, share a layout across pages, and serve CSS and images from a public folder.

Accept form submissions, hold notes in memory, and render them back to the page. Lays the groundwork for SQLite in the next chapter.

Replace the in-memory notes array with Bun's built-in SQLite driver. Notes survive restarts, tests get a clean database every run, and we get our first look at the data on disk.

Reject empty notes, show form errors with the user's input preserved, replace the bare 404 with a styled page, and add a top-level error handler so a broken request never leaks a stack trace.

Add a sign-up form, hash passwords with Bun's built-in argon2id, and store users in the database.

Turn a user account into a session — a login form, a sessions table, a cookie that survives a refresh, a logout route, and a currentUser() helper so the rest of the app can ask who is asking.

Tie every note to a user, gate the routes that create and read them, and let the nav reflect who is logged in — so each account sees only its own notes.

Split the test file along module lines, add edit and delete routes parameterized by note ID, gate them with the same auth-and-ownership pattern, and flash a confirmation message on the redirect home.

Add a search box that filters notes by title or body, page the list so the home page stays readable past a couple of dozen notes, and keep ownership where the last two chapters left it.

Move hardcoded values into environment variables, gate the cookie's secure flag on production, tidy the package.json scripts, and see what bun build can do with a single command.

Push to GitHub, deploy to Railway, get a live HTTPS URL.

Attach a Railway volume so SQLite survives redeploys; view logs.

Same app, different platform — fly launch, volumes, regions.

Where to go from here, and a preview of Book 2.