CMU Meal Estimator

A small single-page web app that estimates how many meal blocks and FLEX dollars a Carnegie Mellon student should have consumed by a given date — and how many should remain — based on their dining plan and time spent on campus.

The tool spreads a plan's totals evenly across the days you're expected to be on campus, then reports three views of that budget: a per-week rate, an amount consumed so far, and an estimated remaining balance, for both meal blocks and FLEX.

Estimates are informational and based on even distribution across on-campus days. They are not official dining balances.

Features

Pick from all eight dining plans (Green, Blue, Red, Yellow, Tartan Flex, Scotty's Choice, Whitfield's Favor, Piper Select).
"As of" date picker that defaults to today and is clamped to the meal period.
Checkboxes for configured breaks ("missing periods") you spent off campus.
A numeric input for any additional days you don't want counted.
Live-updating results — every input recomputes the estimate instantly.
Everything is config-driven: plans, dates, and breaks live in one JSON file. No code changes needed to adjust them.
Dark theme with restrained CMU Tartan-red accents.

Getting started

Requires Node.js 18+.

npm install      # install dependencies
npm run dev      # start the dev server at http://localhost:5173

Other scripts

npm run build    # type-check and produce a production build in dist/
npm run preview  # serve the production build locally
npm test         # run the estimation-engine tests

Configuration

All tunable values live in src/config.json. Edit that file, then reload the page — the UI updates reactively.

{
  "mealStartDate": "2026-08-24",   // first day of the meal period (YYYY-MM-DD)
  "mealEndDate": "2026-12-13",     // last day of the meal period (YYYY-MM-DD)

  "plans": [
    {
      "id": "green",               // stable unique key
      "displayName": "Green",      // shown in the dropdown
      "totalMealBlocks": 210,      // total blocks for the whole meal period
      "totalFlexDollars": 500      // total FLEX dollars for the whole meal period
    }
    // ...more plans
  ],

  "missingPeriods": [
    {
      "id": "fall-break",          // stable unique key
      "displayName": "Fall Break", // shown next to the checkbox
      "startDate": "2026-10-19",   // inclusive
      "endDate": "2026-10-20"      // inclusive
    }
    // ...add as many as you like; each becomes a checkbox
  ]
}

Notes:

The shipped plan numbers are placeholders. Replace totalMealBlocks and totalFlexDollars with the real figures from your CMU dining agreement, and set the correct mealStartDate / mealEndDate for your semester.
Add or remove plans and missing periods freely. Every missing period automatically becomes a checkbox in the UI.
If the config is malformed (missing fields, bad dates, duplicate ids, negative totals), the app shows a readable list of problems instead of rendering broken estimates.

How the estimate works

Total active days = every calendar day in [mealStartDate, mealEndDate], minus the days covered by any break you check.
Daily rate = plan total / total active days, computed separately for blocks and FLEX.
Active days consumed = active days from the start up to your "as of" date, minus checked breaks in that window, minus any additional excluded days.
Consumed = daily rate × active days consumed.
Remaining = plan total − consumed.
Per week = daily rate × 7.

Checking a break or adding excluded days shifts your expected consumption down, which is what you want when you were away and not eating on campus.

Project structure

index.html            # app shell
src/
  config.json         # all tunable values (plans, dates, breaks)
  types.ts            # shared types
  dates.ts            # whole-day date helpers
  configLoader.ts     # validates + normalizes config
  engine.ts           # pure estimation math (no DOM)
  store.ts            # tiny reactive state store
  main.ts             # builds the UI, re-renders on change
  style.css           # dark CMU-accented theme
  engine.test.ts      # engine unit tests
  sanity.test.ts      # checks against the shipped config

Tech stack

Vite for dev server and bundling
TypeScript (strict mode)
Vitest for tests
No UI framework — plain DOM with a small reactive store

Tests

The estimation engine is a set of pure functions, kept separate from the DOM so it can be tested directly:

npm test

Covers day counting across boundaries, budget conservation, monotonicity when excluding days, the zero-active-days (division-by-zero) edge case, and sanity checks against the shipped config.

4.8 KiB Raw Blame History Unescape Escape