Heldinhow Deno Runtime
Overview
Deno is a secure TypeScript runtime built on V8, with built-in tooling and modern JavaScript features. This skill should be invoked when creating JavaScript/TypeScript applications that benefit from TypeScript-first development, built-in testing, and simplified dependency management.
Core Principles
- TypeScript First: Use TypeScript natively without compilation setup
- URL Imports: Import dependencies directly from URLs
- Security by Default: Explicit permissions for file, network, environment access
- Built-in Tools: Use Deno for linting, formatting, testing, and bundling
Preparation Checklist
- Install Deno:
curl -fsSL https://deno.land/x/install/install.sh | sh - Verify installation:
deno --version - Review Deno API differences from Node.js
- Set up editor (VS Code with Deno extension)
Step-by-Step Process
- Initialize: Create TypeScript files directly
- Import: Use URL imports for dependencies
- Write Code: Leverage TypeScript and Deno APIs
- Run: Execute with
deno run --allow-<perm> <file.ts> - Test: Use
deno testfor test suites - Deploy: Deploy to Deno Deploy or Deno-compatible platforms
Do's and Don'ts
- ✅ Do use explicit permissions flags (--allow-read, --allow-net)
- ✅ Do use Deno's built-in formatting:
deno fmt - ✅ Do use Deno's linter:
deno lint - ❌ Don't assume all Node.js packages work
- ❌ Don't use require() - use ES modules only
- ❌ Don't skip permission flags in production
Anti-Patterns
- Node Assumption: Assuming Node.js APIs work identically
- Missing Permissions: Running without required permissions
- NPM Packages: Trying to use npm packages without compatibility layer
- Ignoring Security: Not using Deno's permission system