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Research: Geek Calculator Implementation
Key Unknowns Identified
- Error handling for invalid expressions
- Behavior for calculations that exceed numerical limits
- Limits to calculation history storage
- Specific percentage operation behaviors
- Response to inputs exceeding v1 scope
Research Findings
Decision: Error Handling for Invalid Expressions
Rationale: For invalid expressions like "5 // 0" or "5 + * 3", the calculator will display "Error" in the display area and require clearing before continuing. Alternatives considered: Alternative was to show specific error messages (e.g., "Division by zero", "Invalid syntax") but the simpler "Error" approach maintains the minimal UI aesthetic.
Decision: Overflow and Large Number Handling
Rationale: For calculations that exceed JavaScript's numerical limits, the calculator will show "Infinity" or "-Infinity" for overflow, and "0" for underflow. Alternatives considered: Could have implemented custom large number handling but this would increase code size beyond 50KB target.
Decision: Calculation History Storage
Rationale: History will be stored in localStorage with a limit of 50 entries. When limit is reached, oldest entries are removed. Alternatives considered: Unlimited history was considered but would risk localStorage quota exhaustion and performance degradation.
Decision: Percentage Operation Behavior
Rationale: Percentage operations will follow standard calculator behavior: "100 + 10%" = 110, "50%" = 0.5, "100 * 5%" = 5. Alternatives considered: Scientific calculator percentage behavior (like "100 + 10%" = 100.1) was considered but standard behavior is more familiar to users.
Decision: Handling Out-of-Scope Functions
Rationale: For inputs that exceed v1 scope (like scientific functions), the calculator will display "Error" to maintain focus on core features. Alternatives considered: Ignoring invalid inputs silently was considered but providing feedback is better for user experience.
Technology Decisions
Decision: Vanilla JS Modules Architecture
Rationale: Using ES6 modules will provide clean separation of concerns while maintaining zero dependencies as required by the constitution. Alternatives considered: Single file vs. modular approach; modular was chosen for maintainability despite the single-file requirement for the final deliverable.
Decision: RPN Implementation
Rationale: Implementing RPN with a stack data structure will provide the required functionality while keeping the code efficient. Alternatives considered: String-based RPN processing vs. stack-based; stack-based was chosen for better performance and clearer code.
Decision: Testing Framework
Rationale: A minimal custom test harness will be implemented to avoid external dependencies while providing necessary test coverage. Alternatives considered: External testing libraries like Jest were considered but rejected to maintain zero dependencies requirement.
Decision: Service Worker Strategy
Rationale: A cache-first service worker will ensure full offline functionality as required by the constitution. Alternatives considered: Network-first or stale-while-revalidate strategies were considered but cache-first better ensures offline capability.
Accessibility Implementation
Decision: ARIA Roles and Keyboard Navigation
Rationale: Using semantic HTML with appropriate ARIA roles and comprehensive keyboard event handling will meet WCAG requirements. Alternatives considered: Custom accessibility solutions vs. standard HTML patterns; standard patterns were chosen for better compatibility and maintainability.