Your first Deno project

Initialize a project:

deno init hello-deno
cd hello-deno

hello-deno/
├── deno.json
├── main.ts
└── main_test.ts

Make main.ts expose a testable handler:

export function handler(request: Request): Response {
  const url = new URL(request.url);
  return Response.json({ message: "Hello Deno", path: url.pathname });
}

if (import.meta.main) {
  Deno.serve({ port: 8000 }, handler);
}

Record team commands in deno.json:

{
  "tasks": {
    "dev": "deno run --watch --allow-net=0.0.0.0:8000 main.ts",
    "check": "deno fmt --check && deno lint && deno check main.ts main_test.ts",
    "test": "deno test"
  }
}

deno task check
deno task test
deno task dev

Listening with Deno.serve needs network permission. Unit tests that call handler() directly do not open a port, so they do not need -A.

Next: permissions, web stack selection, and project blueprints.