first deno api endpoint
Create main.ts with Deno.serve. Return JSON {"ok":true} on GET /. Run on port 8000 and verify with curl.
Backend & Runtime / Knowledge library
Deno
secure javascript/typescript runtime for backends
Why learn Deno?
Deno helps backend developers build APIs, scripts, and CLIs with fewer setup steps by combining a secure-by-default runtime, first-class TypeScript, and built-in tooling in one platform.
Where it came from
2018: Ryan Dahl introduced Deno, reflecting on Node.js design tradeoffs. 2020: Deno 1.0 launched with secure-by-default permissions and built-in TypeScript support. 2022-2023: npm and Node compatibility expanded significantly. 2024: Deno 2 emphasized easier migration from Node ecosystems while keeping Deno’s security and DX goals.
- 2018: Ryan Dahl introduced Deno, reflecting on Node.js design tradeoffs.
- 2020: Deno 1.0 launched with secure-by-default permissions and built-in TypeScript support.
- 2022-2023: npm and Node compatibility expanded significantly.
- 2024: Deno 2 emphasized easier migration from Node ecosystems while keeping Deno’s security and DX goals.
Build your understanding
Work through these exercises in order. Try the task before opening a reference.
- Create main.ts with Deno.serve. Return JSON {"ok":true} on GET /. Run on port 8000 and verify with curl.
- Build cli.ts that reads a file path from Deno.args and prints the first 80 characters. Handle missing read permission with a friendly message.
- Create POST /users using Deno.serve and npm:zod. Validate {"name":string,"email":string}. Return 400 for invalid body and 201 for valid body.
- Add deno.json tasks for dev and test. Write at least two deno test cases for your /users route (valid and invalid payload).
- Use deno compile to produce a runnable binary of your CLI. Document required permissions and one sample command.
More ways to practice
permission-aware file cli
Build cli.ts that reads a file path from Deno.args and prints the first 80 characters. Handle missing read permission with a friendly message.
validated post route with npm package
Create POST /users using Deno.serve and npm:zod. Validate {"name":string,"email":string}. Return 400 for invalid body and 201 for valid body.
test and task automation
Add deno.json tasks for dev and test. Write at least two deno test cases for your /users route (valid and invalid payload).
ship a single binary
Use deno compile to produce a runnable binary of your CLI. Document required permissions and one sample command.
Documentation and sources
- Official documentation (docs.deno.com)
- Runtime manual (docs.deno.com)
- Node and npm compatibility (docs.deno.com)
- API reference (docs.deno.com)
- JSR package registry (jsr.io)
Catalog research notes
- Deno 2 focused on smoother Node.js and npm package compatibility.
- JSR became a first-class package registry for modern TypeScript/JavaScript modules.
- Tooling stayed integrated: fmt, lint, test, task, and compile in one runtime.
- Runtime and docs continued aligning with Web APIs to reduce ecosystem lock-in.