Introduction

    It’s built on V8, Rust, and Tokio.

    • Secure by default. No file, network, or environment access (unless explicitly enabled).
    • Supports TypeScript out of the box.
    • Ships a single executable ().
    • Has built-in utilities like a dependency inspector (deno info) and a code formatter (deno fmt).
    • Can bundle scripts into a single JavaScript file.

    Deno aims to be a productive and secure scripting environment for the modern programmer.

    Among other things, Deno is a great replacement for utility scripts that may have been historically written with Bash or Python.

    • Ship as just a single executable ().
    • Provide secure defaults.
      • Unless specifically allowed, scripts can’t access files, the environment, or the network.
    • Be browser-compatible.
      • The subset of Deno programs which are written completely in JavaScript and do not use the global Deno namespace (or feature test for it), ought to also be able to be run in a modern web browser without change.
    • Provide built-in tooling to improve developer experience.
      • E.g. unit testing, code formatting, and linting.
    • Keep V8 concepts out of user land.

    • Deno does not use npm.

      • It uses modules referenced as URLs or file paths.

    • All async actions in Deno return a promise. Thus Deno provides different APIs than Node.

    • Deno requires explicit permissions for file, network, and environment access.

    • Deno uses “ES Modules” and does not support require(). Third party modules are imported via URLs:

    • Fetch and cache remote code upon first execution, and never update it until the code is run with the --reload flag. (So, this will still work on an airplane.)
    • Modules/files loaded from remote URLs are intended to be immutable and cacheable.