skip to content

Python View all 62 →

Python Installation — Quick-Pick

Python Installation — Windows

Python Installation — WSL Ubuntu

Python Installation — macOS

Python Installation — Linux

Virtual Environments — venv

pyproject.toml — Modern Python Project Config

pip — Python Package Installer

Essential Python Packages

requests — HTTP for Humans

httpx — Modern HTTP Client

numpy — Numerical Arrays

pandas — DataFrames

matplotlib — Plotting

scipy — Scientific Computing

Pillow — Image Processing

scikit-learn — Classical Machine Learning

click — CLI Builder

pydantic — Data Validation

sqlalchemy — SQL Toolkit & ORM

JavaScript View all 47 →

Node.js Installation

Node.js Runtime

npm Package Manager

npx — Execute npm Packages

node:fs — File System

node:stream — Streams

Fastify — Node Web Framework

pnpm Package Manager

Yarn Package Manager

package.json Reference

JavaScript Modules

Regular Expressions

Bun — All-in-One JavaScript Runtime & Toolkit

diff2html-cli — Beautiful HTML Diffs from the Terminal

wrangler — Cloudflare Workers CLI

TypeScript View all 27 →

TypeScript Installation & Running

tsconfig.json Reference

Types vs Interfaces

typeof & keyof — Type-level operators

satisfies Operator — Type-check without widening

Mapped & Conditional Types

Discriminated Unions — Tagged Variants & Exhaustiveness

infer Keyword — Extracting types from patterns

Type-Only Imports & Exports

Template Literal Types — String Algebra at the Type Level

Branded Types — Nominal Typing in a Structural System

Common TypeScript Errors

TypeScript Modules — module, moduleResolution, .mts / .cts

.d.ts Files — Ambient Declarations, Asset Imports, Module Typing

Linux View all 49 →

grep — Pattern Search

ripgrep (rg) — Fast Recursive Search

fd — Fast File Finder

find — File Search

sed — Stream Editor

tar — Archive & Compress

vim — Modal Text Editor

awk / gawk — Text Processing

rsync — Fast Incremental File Sync

cut, paste & join — Column Tools

tmux — Terminal Multiplexer

sort, uniq & wc — Counting & Ordering

tr & xargs — Transform and Execute

permissions — chmod, chown, umask, ACLs

cron — Scheduled Jobs

df, du & duf — Disk Usage

bat — Better cat

eza / exa — Modern ls

jq — JSON Processor

curl — HTTP Client

Windows View all 72 →

dir — List Directory Contents

cd — Change Directory

hostname — Print Machine Name

whoami — Current User Identity

set — Environment Variables

echo — Output Text and Control Command Echo

findstr — Search Text in Files

fc — File Compare

cls — Clear Console Screen

copy — Copy Files

xcopy — Extended Copy

robocopy — Robust File Copy

del — Delete Files

rmdir / rd — Remove Directory

mkdir / md — Make Directory

move — Move and Rename Files

ipconfig — IP Configuration

ping — Test Network Connectivity

tracert — Trace Network Route

netstat — Network Connections and Statistics

z/OS View all →

SDSF — Spool Display and Search Facility

DFSORT — Sort, Merge, and ICETOOL

GDG — Generation data groups for rolling datasets

IDCAMS — Access Method Services for VSAM

IEBCOPY — Partitioned dataset copy, compress, and unload

JCL DD Statement — Deep Reference

JES2 — Operator commands and subsystem control

RACF — z/OS Security Administration

ISPF Edit — Primary commands, line commands, macros, and column-mode editing

USS — z/OS UNIX System Services

Zowe CLI — Modern z/OS DevOps from your laptop

Db2 SPUFI — Interactive SQL, DSN commands, BIND, and catalog queries on z/OS

CICS CEMT — Master Terminal Operator Reference

DFSMShsm — Hierarchical Storage Manager

z/OS TCP/IP — NETSTAT, PING, Profile, and Diagnostics

JCL Quick Reference

TSO/ISPF Navigation

z/OS FTP Reference

macOS View all →

macOS CLI — Command Line Reference

sips — Scriptable Image Processing

diskutil — macOS Disk & APFS Management

networksetup — macOS Network Configuration

codesign — macOS Code Signing, Notarization & Stapling

xattr — Extended Attributes on macOS

defaults — macOS Preferences From the Command Line

duti — Set Default Applications on macOS

Homebrew — The Missing Package Manager for macOS

launchctl — Managing launchd Agents and Daemons

softwareupdate — macOS Updates From the Terminal

caffeinate — Keep macOS Awake on Demand

mdfind — Spotlight Search From the Terminal

system_profiler — macOS Hardware & Software Inventory

pbcopy & pbpaste — macOS Clipboard CLI

pmset — macOS Power Management

osascript — Run AppleScript and JXA From the Shell

tmutil — Time Machine from the Command Line

Claude Code View all →

Claude Code Overview

Claude Code CLI — Complete Command-Line Reference

Claude Code Slash Commands

Claude Code Settings and Permissions

Claude Code Subagents

Claude Code Hooks

Claude Code Skills

Claude Code MCP Servers

Claude Code Statusline

Claude Code Power-User Tips

Codex CLI View all →

Codex CLI Overview

Codex Configuration

codex exec — Non-Interactive Mode

Codex Slash Commands

Approvals & Sandboxing

Codex MCP Servers

Codex Tips & AGENTS.md

Codex Sub-Agents & Task Delegation

Claude API View all →

Claude API — Python

Claude API — TypeScript SDK

Claude Tool Use (Function Calling)

Claude API — Streaming

Claude API — Message Batches

Claude API — Prompt Caching

Claude API — Files

Prompting View all →

Prompt Engineering Patterns

RAG Implementation Checklist

LLM Evaluations

Few-Shot Prompting

Chain-of-Thought Prompting

Structured Output

Frameworks View all →

transformers — Hugging Face

google-generativeai — Gemini SDK

LangChain — LLM Application Framework

LangSmith — LLM Observability & Evaluation

Haystack 2.x — Pipelines for LLM Applications

DSPy — Programmatic Prompting and Optimisation

Semantic Kernel — Microsoft's AI Orchestration SDK

MCP Frameworks — Servers, Clients, and Transports

Agent Frameworks Comparison — Decision Matrix

Pip (Python) View all 74 →

anyio — Structured Concurrency Across asyncio and trio

attrs — Classes Without Boilerplate

autogen-agentchat — Microsoft AutoGen v0.4 Multi-Agent SDK

beautifulsoup4 — HTML/XML Parsing Library

black — The Uncompromising Python Formatter

boto3 — AWS SDK for Python

certifi — Mozilla CA Certificate Bundle

cffi — C Foreign Function Interface for Python

charset-normalizer — Character Encoding Detection

chromadb — Embedded Vector Database

click — Composable Command-Line Builder

crewai — Role-Based Multi-Agent Orchestration

cryptography — Recipes and Hazmat for Python Crypto

dagster — Asset-Oriented Data Orchestration

django — The Batteries-Included Web Framework

dspy — Declarative LLM Programming

duckdb — Embedded Analytical SQL

fastapi — Modern ASGI API Framework

flask — The WSGI Microframework

fsspec — Filesystem Spec Abstraction

npm (Node) View all 68 →

ccusage — Claude Code & Coding-Agent Token Usage Analyzer

@biomejs/biome — Rust-based unified linter + formatter

@playwright/test — End-to-end browser testing

@vue/cli — Vue 2/3 scaffolding CLI (deprecated path)

ai — Vercel AI SDK

astro — Content-First Web Framework

axios — Promise-Based HTTP Client for Node and the Browser

body-parser — HTTP Request Body Parsing for Node

chalk — Terminal String Styling for Node

commander — Node.js Command-Line Builder

concurrently — Run multiple npm scripts in parallel

cors — CORS Middleware for Node

cypress — Front-end E2E testing with a live browser UI

dayjs — Tiny Immutable Date Library

debug — namespaced runtime logger

diff2html-cli — HTML Diffs from the Terminal

dotenv — Load .env files into process.env

drizzle-orm — TypeScript SQL Toolkit

effect — TypeScript Library for Effect Systems

elysia — Ergonomic Bun-Native Web Framework

Cargo (Rust) View all →

Go modules View all →

OS 7 concepts

Cloud Computing DevOps DNS Filesystems JSON Pipes Regular Expressions

AI 4 concepts

AI Agents APIs Claude Code Retrieval-Augmented Generation (RAG)

Programming 2 concepts

Asynchronous Programming HTTP

All concepts (13) → View concept graph →

[ new ] [ categories ] [ glossary ] [ graph ] [ tags ]

Navigation

Python Installation — Quick-Pick Python Installation — Windows Python Installation — WSL Ubuntu Python Installation — macOS Python Installation — Linux Virtual Environments — venv pyproject.toml — Modern Python Project Config pip — Python Package Installer Essential Python Packages requests — HTTP for Humans httpx — Modern HTTP Client numpy — Numerical Arrays pandas — DataFrames matplotlib — Plotting scipy — Scientific Computing Pillow — Image Processing scikit-learn — Classical Machine Learning click — CLI Builder pydantic — Data Validation sqlalchemy — SQL Toolkit & ORM + 42 more →

Node.js Installation Node.js Runtime npm Package Manager npx — Execute npm Packages node:fs — File System node:stream — Streams Fastify — Node Web Framework pnpm Package Manager Yarn Package Manager package.json Reference JavaScript Modules Array Methods Async / Await Regular Expressions Promises Fetch API Error Handling Bun — All-in-One JavaScript Runtime & Toolkit diff2html-cli — Beautiful HTML Diffs from the Terminal wrangler — Cloudflare Workers CLI + 27 more →

TypeScript Installation & Running tsconfig.json Reference Types vs Interfaces Generics Utility Types Type Narrowing typeof & keyof — Type-level operators satisfies Operator — Type-check without widening Type Guards Mapped & Conditional Types Discriminated Unions — Tagged Variants & Exhaustiveness infer Keyword — Extracting types from patterns Type-Only Imports & Exports Enums Template Literal Types — String Algebra at the Type Level Branded Types — Nominal Typing in a Structural System Decorators Common TypeScript Errors TypeScript Modules — module, moduleResolution, .mts / .cts .d.ts Files — Ambient Declarations, Asset Imports, Module Typing + 7 more →

grep — Pattern Search ripgrep (rg) — Fast Recursive Search fd — Fast File Finder find — File Search sed — Stream Editor tar — Archive & Compress vim — Modal Text Editor awk / gawk — Text Processing rsync — Fast Incremental File Sync cut, paste & join — Column Tools tmux — Terminal Multiplexer sort, uniq & wc — Counting & Ordering tr & xargs — Transform and Execute permissions — chmod, chown, umask, ACLs cron — Scheduled Jobs df, du & duf — Disk Usage bat — Better cat eza / exa — Modern ls jq — JSON Processor curl — HTTP Client + 29 more →

dir — List Directory Contents cd — Change Directory hostname — Print Machine Name whoami — Current User Identity set — Environment Variables echo — Output Text and Control Command Echo findstr — Search Text in Files fc — File Compare cls — Clear Console Screen copy — Copy Files xcopy — Extended Copy robocopy — Robust File Copy del — Delete Files rmdir / rd — Remove Directory mkdir / md — Make Directory move — Move and Rename Files ipconfig — IP Configuration ping — Test Network Connectivity tracert — Trace Network Route netstat — Network Connections and Statistics + 52 more →

SDSF — Spool Display and Search Facility DFSORT — Sort, Merge, and ICETOOL GDG — Generation data groups for rolling datasets IDCAMS — Access Method Services for VSAM IEBCOPY — Partitioned dataset copy, compress, and unload JCL DD Statement — Deep Reference JES2 — Operator commands and subsystem control RACF — z/OS Security Administration ISPF Edit — Primary commands, line commands, macros, and column-mode editing USS — z/OS UNIX System Services Zowe CLI — Modern z/OS DevOps from your laptop Db2 SPUFI — Interactive SQL, DSN commands, BIND, and catalog queries on z/OS CICS CEMT — Master Terminal Operator Reference DFSMShsm — Hierarchical Storage Manager z/OS TCP/IP — NETSTAT, PING, Profile, and Diagnostics JCL Quick Reference REXX Snippets TSO/ISPF Navigation z/OS FTP Reference

macOS CLI — Command Line Reference sips — Scriptable Image Processing diskutil — macOS Disk & APFS Management networksetup — macOS Network Configuration codesign — macOS Code Signing, Notarization & Stapling xattr — Extended Attributes on macOS defaults — macOS Preferences From the Command Line duti — Set Default Applications on macOS Homebrew — The Missing Package Manager for macOS launchctl — Managing launchd Agents and Daemons softwareupdate — macOS Updates From the Terminal caffeinate — Keep macOS Awake on Demand mdfind — Spotlight Search From the Terminal system_profiler — macOS Hardware & Software Inventory pbcopy & pbpaste — macOS Clipboard CLI pmset — macOS Power Management osascript — Run AppleScript and JXA From the Shell tmutil — Time Machine from the Command Line

Claude Code Overview Claude Code CLI — Complete Command-Line Reference Claude Code Slash Commands Claude Code Settings and Permissions Claude Code Subagents Claude Code Hooks Claude Code Skills Claude Code MCP Servers Claude Code Statusline Claude Code Power-User Tips

Codex CLI Overview Codex Configuration codex exec — Non-Interactive Mode Codex Slash Commands Approvals & Sandboxing Codex MCP Servers Codex Tips & AGENTS.md Codex Sub-Agents & Task Delegation

Claude API — Python Claude API — TypeScript SDK Claude Tool Use (Function Calling) Claude API — Streaming Claude API — Message Batches Claude API — Prompt Caching Claude API — Files

Prompt Engineering Patterns RAG Implementation Checklist LLM Evaluations Few-Shot Prompting Chain-of-Thought Prompting Structured Output

transformers — Hugging Face google-generativeai — Gemini SDK LangChain — LLM Application Framework LangSmith — LLM Observability & Evaluation Haystack 2.x — Pipelines for LLM Applications DSPy — Programmatic Prompting and Optimisation Semantic Kernel — Microsoft's AI Orchestration SDK MCP Frameworks — Servers, Clients, and Transports Agent Frameworks Comparison — Decision Matrix

Pip (Python) 74

anyio — Structured Concurrency Across asyncio and trio attrs — Classes Without Boilerplate autogen-agentchat — Microsoft AutoGen v0.4 Multi-Agent SDK beautifulsoup4 — HTML/XML Parsing Library black — The Uncompromising Python Formatter boto3 — AWS SDK for Python certifi — Mozilla CA Certificate Bundle cffi — C Foreign Function Interface for Python charset-normalizer — Character Encoding Detection chromadb — Embedded Vector Database click — Composable Command-Line Builder crewai — Role-Based Multi-Agent Orchestration cryptography — Recipes and Hazmat for Python Crypto dagster — Asset-Oriented Data Orchestration django — The Batteries-Included Web Framework dspy — Declarative LLM Programming duckdb — Embedded Analytical SQL fastapi — Modern ASGI API Framework flask — The WSGI Microframework fsspec — Filesystem Spec Abstraction + 54 more →

ccusage — Claude Code & Coding-Agent Token Usage Analyzer @biomejs/biome — Rust-based unified linter + formatter @playwright/test — End-to-end browser testing @vue/cli — Vue 2/3 scaffolding CLI (deprecated path) ai — Vercel AI SDK astro — Content-First Web Framework axios — Promise-Based HTTP Client for Node and the Browser body-parser — HTTP Request Body Parsing for Node chalk — Terminal String Styling for Node commander — Node.js Command-Line Builder concurrently — Run multiple npm scripts in parallel cors — CORS Middleware for Node cypress — Front-end E2E testing with a live browser UI dayjs — Tiny Immutable Date Library debug — namespaced runtime logger diff2html-cli — HTML Diffs from the Terminal dotenv — Load .env files into process.env drizzle-orm — TypeScript SQL Toolkit effect — TypeScript Library for Effect Systems elysia — Ergonomic Bun-Native Web Framework + 48 more →

OS 7

Cloud Computing DevOps DNS Filesystems JSON Pipes Regular Expressions

AI 4

AI Agents APIs Claude Code Retrieval-Augmented Generation (RAG)

Programming 2

Asynchronous Programming HTTP

All concepts (13) → View concept graph →

[ new ] [ categories ] [ glossary ] [ graph ] [ tags ]

home / javascript / Day.js — Tiny, immutable date library / graph

Graph: Day.js — Tiny, immutable date library

Showing connections up to depth 2 from this page.

Loading graph…

Jockey — Jay's Cheat Sheets & Snippets

esc

↑↓ navigate ↵ open

keyboard shortcuts

navigation

g h	home
g p	Programming section
g p	Python section
g j	JavaScript section
g t	TypeScript section
g o	OS section
g l	Linux section
g w	Windows section
g z	z/OS section
g o	macOS section
g a	AI section
g c	Claude Code section
g c	Codex CLI section
g c	Claude API section
g p	Prompting section
g f	Frameworks section
g p	Packages section
g p	Pip (Python) section
g p	npm (Node) section
g p	Cargo (Rust) section
g p	Go modules section
g g	graph view
g t	tags index

actions

⌘K / /	open search palette
t	cycle theme (dark → light → system)
?	toggle this panel

cheat sheet pages

[ / ]	previous / next sheet in section
j / k	scroll down / up

chords: press first key, then second key within 1 s