A comprehensive toolkit for the Deno 2.x JavaScript/TypeScript runtime, covering installation, permissions, built-in APIs, development tools (task runner, test runner, lint, fmt), TypeScript support, npm integration, workspaces, and deployment patterns. Use when building applications with Deno, managing Deno projects, working with Deno's standard library (@std on JSR), configuring permissions, or deploying to Deno Deploy.
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A comprehensive toolkit for the Deno 2.x JavaScript/TypeScript runtime, covering installation, permissions, built-in APIs, development tools (task runner, test runner, lint, fmt), TypeScript support, npm integration, workspaces, and deployment patterns. Use when building applications with Deno, managing Deno projects, working with Deno's standard library (@std on JSR), configuring permissions, or deploying to Deno Deploy.
Deno 2.7.14
Overview
Deno (pronounced dee-no) is an open-source JavaScript, TypeScript, and WebAssembly runtime built on V8, Rust, and Tokio. It provides secure defaults, first-class TypeScript support, a robust built-in toolchain, and full Node.js/npm compatibility. Deno 2.x represents the current major version with enhanced performance, improved npm integration, and workspace support.
Key features:
TypeScript-ready out of the box — zero config needed
Secure by default — no filesystem, network, or environment access without explicit permission
Built-in toolchain — test runner, linter, formatter, bundle, compile
Node.js and npm compatible — import npm packages with npm: specifiers
JSR integration — first-party package registry at jsr.io
Standard library — modular @std packages published on JSR
Notable Changes in 2.7.14 (since 2.7.0)
Delta updates via bsdiff patches for faster deno upgrade
Alpha and beta release channels supported
node:repl module implemented
llhttp-based node:http rewrite with native TCPWrap
Native TLSWrap (Rust core) and native uv_pipe_t implementation
V8 updated to 146.8.0 with foreground task ownership
Function coverage added to test summary and HTML reports
OpenTelemetry console exporter and array attribute support
P-521 elliptic curve sign, verify, and ECDH derive in ext/crypto
node:http rewritten using llhttp parser with native C++ bindings
fs.Utf8Stream added to ext/node
CacheStorage.keys() and Cache.keys() methods implemented
deno doc now supports npm packages
--cpu-prof flags for CPU profiling
Auto-detect CJS vs ESM in deno eval
Compile config gains include and exclude fields
When to Use
Building JavaScript/TypeScript applications with a modern, secure runtime
Migrating Node.js projects to Deno (full npm compatibility)
Writing CLI tools, HTTP servers, or scripts with built-in tooling
Working with TypeScript without separate compilation steps
Deploying serverless applications to Deno Deploy
Managing monorepo projects with workspace support
Needing a batteries-included runtime with no external dependencies
Core Concepts
Permissions model: Deno denies all I/O by default. Use --allow-read, --allow-write, --allow-net, --allow-env, and --allow-run flags to grant access. Permissions can also be configured in deno.json.
JSR packages: import { x } from "jsr:@std/assert@^1.0.0"
npm packages: import { x } from "npm:chalk@5"
Node built-ins: import fs from "node:fs"
Configuration: The deno.json (or deno.jsonc) file configures imports, tasks, linting, formatting, permissions, and TypeScript compiler options. Deno also supports package.json for Node.js compatibility.
Standard library: Published as modular @std packages on JSR. Key packages include @std/assert, @std/fs, @std/http, @std/path, @std/async, and many more.
Installation / Setup
Install Deno using the official install script:
# macOS and Linux
curl -fsSL https://deno.land/install.sh | sh
# Windows (PowerShell)
irm https://deno.land/install.ps1 | iex
Verify installation:
deno --version
Additional installation options include package managers (Homebrew, Chocolatey, npm), binary downloads from GitHub releases, and APT/YUM repositories → Installation for details.
import chalk from"npm:chalk@5";
console.log(chalk.green("Hello from npm in Deno"));
Using the standard library:
import { assertEquals } from"jsr:@std/assert";
import { walk } from"jsr:@std/fs/walk";
// Walk a directoryforawait (const entry ofwalk("./src")) {
console.log(entry.path);
}
Configuration with bare specifiers:
// deno.json{"imports":{"@std/assert":"jsr:@std/assert@^1.0.0","chalk":"npm:chalk@5"},"tasks":{"start":"deno run --allow-net server.ts","test":"deno test --allow-read","lint":"deno lint"}}
// Now use bare specifiersimport { assertEquals } from"@std/assert";
import chalk from"chalk";
