geek-calc/specs/001-build-a-single/quickstart.md

Quickstart: Geek Calculator

Running the Calculator

1. Open index.html in any modern web browser
2. The calculator will load with a dark terminal-themed UI
3. Begin typing calculations or use mouse/touch to operate

Basic Operations

• Addition: 5 + 3 = → displays 8
• Subtraction: 10 - 4 = → displays 6
• Multiplication: 6 * 7 = → displays 42
• Division: 15 / 3 = → displays 5
• Parentheses: (2 + 3) * 4 = → displays 20
• Percentage: 100 + 10% = → displays 110
• Sign Toggle: Enter number then press ± or +/- button

RPN Mode

1. Toggle RPN mode using the RPN button
2. Enter numbers followed by operators
3. Example: To calculate 4 + 6: 4 ENTER 6 +
4. Use ENTER to push numbers onto the RPN stack
5. Available operations: +, -, *, /

Keyboard Controls

• Numbers: 0-9 keys
• Operators: +, -, *, / keys
• Equals: = or Enter key
• Clear: Escape or C key
• All Clear: Shift + C or Double Escape
• Decimal Point: . key
• Backspace: Backspace key
• RPN Enter: Enter key in RPN mode
• Toggle RPN: R key
• Command Palette: @ key
• History: ↑ and ↓ arrow keys
• Help/Shortcuts: ? key

Command Palette

• Press @ to open the command palette
• Type commands like "clear", "history", "theme", etc.
• Provides quick access to calculator functions

History Feature

• Previous calculations appear in history panel
• Use ↑ and ↓ arrow keys to navigate
• Click on history items to re-run calculations
• Limited to 50 most recent entries

Accessibility Features

• Full keyboard navigation
• ARIA labels on all controls
• High contrast mode
• Screen reader compatible
• Visible focus indicators

Troubleshooting

• If you see "Error", check your expression syntax
• For division by zero, the result will show "Infinity"
• If calculator doesn't respond, try clearing with Escape
• For offline use, ensure service worker is enabled in your browser

Testing

• Unit tests for core math operations: Run tests/index.html in browser
• Tests cover basic arithmetic, RPN operations, and error conditions