Turnip Prophet

A turnip price predictor for Animal Crossing: New Horizons.

This is a fork of mikebryant/ac-nh-turnip-prices — huge thanks to Mike Bryant and all the original contributors for building the foundation of this project. The prediction logic is based on Ninji's reverse engineering of the game's turnip pricing algorithm.

What's changed in this fork

• Expected value calculations — shows the probability-weighted expected price for each time slot, so you can see what a "typical" outcome looks like rather than just the min/max range
• Sell/buy decision advice — compares your current price against the expected future maximum and tells you whether to sell now or wait
• Pattern likelihood indicator — as you enter prices throughout the week, shows which pattern you're most likely on and how confident the prediction is
• Dismissable welcome message — the intro dialog can be closed and won't reappear until you reset
• Hamburger menu — language, theme, and credits moved to a slide-out drawer to reduce clutter
• High color contrast mode — toggle for colorblind-friendly table colors, works with light and dark themes
• Auto-updating URL — the browser URL updates as you enter prices, making sharing easier
• Sticky table header — column headers stay visible when scrolling through pattern results
• Accessibility overhaul:
  • Skip-to-content link for keyboard navigation
  • Proper landmark elements (<main>, <header>, labeled <nav>)
  • Visible focus indicators on all interactive elements
  • Keyboard-accessible menu drawer with focus trapping and Escape key support
  • Screen reader announcements for dynamic results, errors, and notifications (aria-live, role="alert")
  • Accessible chart canvas (role="img" with aria-label)
  • Radio groups wrapped in <fieldset>/<legend> for screen reader context
  • Properly associated labels on all form controls
  • Decorative SVGs hidden from screen readers
  • Keyboard-focusable permalink button
• Bug fix: Pattern 3 middle peak — the minimum prediction for Small Spike's middle peak slot was off by 1 bell vs the game code
• Bug fix: PDF.decay() division by zero — equal min/max decay rates no longer produce NaN
• German translation fix — corrected "large spike" and "small spike" pattern names
• Updated dependencies — jQuery 3.7.1, Chart.js 4.5.0, i18next 25, replaced deprecated i18next-xhr-backend with i18next-http-backend
• Removed Google Analytics — the UA tracking tag was deprecated
• Improved PWA setup — complete precache file list, proper cache versioning, manifest fields
• Comprehensive test suite — 324 tests covering prediction logic, expected values, pattern detection, UI functions, and accessibility
• CI pipeline — GitHub Actions runs tests on PRs and pushes; pre-push hook runs tests locally

Running locally

npx serve

Running tests

npm install
npm test
npm run test:coverage

Contributing

See the contributors to this fork.