Quickstart
Install (once)
curl -fsSL https://www.fairyfly.dev/install.sh | sh
Prebuilt for macOS (Apple silicon / Intel) and Linux (x86_64 / ARM64),
SHA-256 verified, installs to ~/.local/bin/ff. Docker and source builds:
Installation.
Run a file
Create hello.js:
// hello.js
console.log("hello from fairyfly");
Run it:
ff hello.js
# hello from fairyfly
Note: There is no bundled examples/ directory — always create the file first (or scaffold with ff init -y demo).
Run inline code
ff -e 'console.log("hello from fairyfly")'
# hello from fairyfly
Minimal server
Create server.js:
// server.js
http.serve({ port: 3000 }, (url, method, body) => {
const path = url.split("?")[0];
if (path === "/") return { status: 200, body: "hello from fairyfly" };
return { status: 404, body: "not found" };
});
Run it:
Test it in another terminal:
curl http://127.0.0.1:3000/
# hello from fairyfly
curl http://127.0.0.1:3000/nope
# not found
The handler receives (url, method, body) strings and returns a Response (or a { status, body } object, as above). Full contract: HTTP Server guide.
SQLite
// todos.js
const db = Database.open("app.db");
db.execNoArgs("CREATE TABLE IF NOT EXISTS todos (id INTEGER PRIMARY KEY, text TEXT, done INTEGER)");
db.exec("INSERT INTO todos (text, done) VALUES (?, ?)", ["Buy milk", 0]);
console.log(JSON.stringify(db.rows("SELECT * FROM todos"), null, 2));
db.close();
ff todos.js
# [ { id: 1, text: "Buy milk", done: 0 } ]
No packages to install. SQLite is built into the runtime — full reference: SQLite API.
Timers
setTimeout(() => console.log("once"), 100);
const iv = setInterval(() => console.log("tick"), 50);
setTimeout(() => clearInterval(iv), 250);
Max 128 live timers. Full guide: Timers.
Console
console.log("plain", 1, true, null);
console.info("info", "line");
console.debug("debug", "line");
console.warn("warned", "here");
console.error("errored", 42);
Methods: log, info, debug, warn, error, slops, redbal, detail. All return undefined.
Microtasks
queueMicrotask(() => console.log("microtask"));
console.log("sync");
Output:
No process.nextTick. Use queueMicrotask.
Next steps
