deno

# Deno Use Deno as the default runtime/tooling when the repo contains `deno.json`/`deno.jsonc`, uses `deno.lock`, or scripts/documentation reference `deno task`, `deno run`, `deno test`, etc. ## Quick decision rules - Prefer `deno task <name>` if the repo defines tasks. - Use `deno add` / `deno remove` to manage dependencies (writes to config). - Be explicit about permissions for `deno run` / `deno test`. ## Common operations ### Initialize a new project ```bash deno init ``` ### Add dependencies (JSR and npm) ```bash # JSR (recommended for Deno-first packages) deno add jsr:@std/path # npm packages are supported too deno add npm:react # multiple at once deno add jsr:@std/assert npm:chalk ``` ### Remove dependencies ```bash deno remove jsr:@std/path ``` ### Run a script ```bash # Minimal permissions: only what the program needs # Examples: # --allow-net=api.example.com # --allow-read=./data # --allow-env=FOO,BAR deno run --allow-net --allow-read main.ts ``` ### Run tasks ```bash # list tasks deno task # run a task defined in deno.json/deno.jsonc deno task dev ``` ### Formatting, linting, testing ```bash deno fmt deno lint deno test # common permissioned test run deno test --allow-net --allow-read ``` ### Install / run CLIs ```bash # Run a JSR or npm package's CLI without installing globally deno x jsr:@std/http/file-server -p 8080 # Install globally (requires choosing permissions at install time) # Prefer the smallest set of permissions; avoid blanket flags unless necessary. deno install -g -N -R jsr:@std/http/file-server -- -p 8080 ``` ## Notes / pitfalls - Deno is secure-by-default: missing permissions cause runtime errors; add the smallest set of `--allow-*` flags needed. - Dependency specifiers: - `jsr:` for JSR registry packages - `npm:` for npm packages - URL imports are also supported (and cached) - Lockfile: `deno.lock` helps ensure reproducible dependency resolution.