deno

secure runtime for JavaScript and TypeScript

TLDR

Run a TypeScript/JavaScript file

$ deno run [script.ts]

Run with network permission

$ deno run --allow-net [script.ts]

Run with all permissions

$ deno run -A [script.ts]

Start REPL

$ deno repl

Run remote script

$ deno run [https://example.com/script.ts]

Compile to executable

$ deno compile [script.ts]

Format source files

$ deno fmt

Run tests

$ deno test

Start an HTTP server (using default export)

$ deno serve [script.ts]

Add a dependency

$ deno add [npm:package-name]

Initialise a new project

$ deno init [project-name]

SYNOPSIS

deno subcommand [options] [script] [args]

Deno is a secure runtime for JavaScript and TypeScript. It executes code in a sandboxed environment where permissions for file, network, and environment access must be explicitly granted.Deno features native TypeScript support without configuration, a built-in formatter and linter, test runner, and standard library. It uses ES modules exclusively and can import modules directly from URLs, eliminating the need for a package manager.The runtime is built on V8 and Rust, emphasizing security and modern JavaScript features. It provides Web API compatibility, making code more portable between Deno and browser environments.Deno 2 added a built-in package manager (`deno add`, `deno remove`) with support for npm and JSR packages, and a `deno serve` subcommand for running HTTP servers. The generic `--unstable` flag was replaced by per-feature granular flags.

PARAMETERS

SUBCOMMAND

Command: run, repl, serve, compile, test, fmt, lint, add, remove, install, init, doc, info, task, publish, upgrade, etc.

SCRIPT

TypeScript/JavaScript file or URL to execute.

--allow-net [HOSTS]

Allow network access.

--allow-read [PATHS]

Allow filesystem read access.

--allow-write [PATHS]

Allow filesystem write access.

--allow-env [VARS]

Allow environment variable access.

-A, --allow-all

Allow all permissions.

--unstable-FEATURE

Enable a specific unstable API feature (e.g. `--unstable-kv`, `--unstable-ffi`). The generic `--unstable` flag was removed in Deno 2.

--watch

Watch for changes and restart.

--help

Display help information.

CONFIGURATION

deno.json or deno.jsonc

Project configuration file for import maps, tasks, compiler options, and formatting rules.

CAVEATS

Not fully compatible with Node.js modules. Some npm packages require compatibility layers. Permission flags must be specified for each resource type. URL imports depend on remote availability.

HISTORY

Deno was created by Ryan Dahl, the original creator of Node.js, and announced in 2018. It was designed to address perceived shortcomings in Node.js, particularly around security, TypeScript support, and module systems. Version 1.0 was released in 2020.