#+TITLE: Quick Reference Guide
#+DESCRIPTION: Cheat sheet for common commands and shortcuts

* Command Line
** Git Commands
*** Basic Operations
**** Status and Changes
- =git status= - Show working tree status
- =git diff= - Show changes between commits
- =git log --oneline= - Compact commit history

**** Staging and Committing  
- =git add .= - Stage all changes
- =git commit -m "message"= - Commit with message
- =git push origin main= - Push to remote

*** Branching
- =git branch= - List branches
- =git checkout -b feature= - Create and switch to branch
- =git merge feature= - Merge branch into current

** NPM Commands
*** Package Management
- =npm install= - Install dependencies
- =npm install -D package= - Install dev dependency
- =npm uninstall package= - Remove package

*** Scripts
- =npm run dev= - Start development server
- =npm run build= - Build for production
- =npm test= - Run tests

* Keyboard Shortcuts
** VS Code
*** Navigation
- =Ctrl+P= - Quick file open
- =Ctrl+Shift+P= - Command palette  
- =Ctrl+G= - Go to line

*** Editing
- =Ctrl+D= - Select next occurrence
- =Ctrl+/= - Toggle comment
- =Alt+Shift+Down= - Duplicate line

** Browser DevTools
*** Elements Tab
- =H= - Hide element
- =Delete= - Delete element
- =F2= - Edit as HTML

*** Console
- =Ctrl+L= - Clear console
- =$0= - Reference selected element
- =console.table(data)= - Display data as table

* Regular Expressions
** Common Patterns
*** Text Matching
- =\d+= - One or more digits
- =\w+= - One or more word characters
- =\s+= - One or more whitespace

*** Anchors
- =^= - Start of line
- =$= - End of line  
- =\b= - Word boundary

** Examples
*** Email Validation
=^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$=

*** Phone Number
=^\d{3}-\d{3}-\d{4}$=

* CSS Selectors
** Basic Selectors
- =.class= - Class selector
- =#id= - ID selector
- =element= - Element selector

** Combinators
- =parent > child= - Direct child
- =ancestor descendant= - Any descendant
- =element + next= - Adjacent sibling

** Pseudo-classes
- =:hover= - Mouse hover state
- =:first-child= - First child element
- =:nth-child(n)= - Nth child element

* HTTP Status Codes
** 2xx Success
- =200= - OK
- =201= - Created
- =204= - No Content

** 4xx Client Error  
- =400= - Bad Request
- =401= - Unauthorized
- =404= - Not Found

** 5xx Server Error
- =500= - Internal Server Error
- =502= - Bad Gateway
- =503= - Service Unavailable

* Org Mode Syntax
** Headings
- =*= - Level 1 heading
- =**= - Level 2 heading
- =***= - Level 3 heading

** Lists
*** Unordered
- Dash, plus, or asterisk

*** Ordered
1. Numbers with dot or parenthesis

*** Checkboxes
- =[ ]= - Empty checkbox
- =[X]= - Checked checkbox

** Markup
- =*bold*= - Bold text
- =/italic/= - Italic text  
- ==code== - Inline code
- =~verbatim~= - Verbatim text

** Links
- =[[URL][Description]]= - External link
- =[[file:path]]= - File link
- =[[*Heading]]= - Internal link to heading