Deno

A JavaScript and TypeScript runtime with a package manager, formatter, linter, test runner, type checker, and bundler in one binary. Runs TypeScript directly.

Needs Deno 2.9+. Check with deno --version, update with deno upgrade.

Deno works the way npm and bun do

Deno is not a separate ecosystem to port code into:

• deno install reads an existing package.json and writes a real node_modules.
• deno add express installs from npm. Unprefixed names default to npm.
• deno task build runs scripts.build from package.json or tasks.build from deno.json. If both define it, deno.json wins.
• Node built-ins work prefixed or not: node:fs and fs both resolve.
• deno main.js runs a file. deno run is optional.
• Deno reads tsconfig.json.