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matejhron edited this page May 10, 2026 · 2 revisions

DecoJS is a browser-based educational tool and dive planner implementing Bühlmann ZH-L16 (variants A/B/C) with Erik Baker gradient factors. It combines three interactive sandboxes, four theory lessons, and seven CMAS/SPČR exam-style quizzes in a single Progressive Web App — no server, no build step, no framework.

Three sections

  • Sandbox (sandbox/index.html plus four secondary simulators) — interactive dive planner where users freely configure gases, gradient factors, and a waypoint profile. The editor produces a single JSON dive setup that feeds the dive profile chart, the M-value (P-P) chart, and the instantaneous-GF chart.
  • Theory (pressure.html, tissue-loading.html, m-values.html, gradient-factors.html) — four HTML lessons covering the physics for end-users, embedding the same chart components to demonstrate worked examples. Each example links back to Sandbox with a matching setup.
  • Tests (quiz-*.html) — seven quizzes driven by the official SPČR (Czech CMAS) 2018 exam question banks (physics, anatomy, accidents, safety, training, equipment, vessel), powered by a generic quiz engine with category filters and scoring.

Running locally

There is no bundler. The project is loaded as ES modules directly by the browser, which means files must be served over HTTP (not file://).

npm install   # only pulls jest for `npm test`; not needed to run the app

Serve the repo root with any static server. The convention used in development is the VS Code Live Server extension on port 5500 — open any HTML file and "Go Live". Alternatives: python3 -m http.server 5500, npx http-server -p 5500, or similar. No build step, no watch process.

Running tests

npm test

This runs node tests/run-tests.mjs — a custom zero-dependency test runner with Jest-style describe/test/expect. The suite covers 208 tests across four files:

  • tests/decoModel.test.js — pressure, Haldane, Schreiner, M-values, GF, ceilings, deco schedule
  • tests/diveSetup.test.js — gas library, waypoints, MOD, SAC
  • tests/diveProfile.test.js — profile validation and statistics
  • tests/decotengu-comparison.test.mjs — 3900 Bühlmann-air scenarios pre-generated from decotengu 0.14.1 as the numerical oracle

See Validation-and-Testing for details on tolerances and scenario coverage.

Before every commit

Bump the version badge so users can see the right version in the footer: edit css/styles.css — search for .version-number::after and update content:.

Run npm test — all 208 tests must pass — then commit alongside the feature change.

Project layout

  • js/ — all application code. Core algorithm in decoModel.js, tissueCompartments.js, diveSetup.js, diveProfile.js; UI modules under js/components/ and js/charts/; quiz engine in quiz.js; i18n in i18n.js; navigation in nav.js.
  • tests/ — test runner and four test files plus the 3900-scenario decotengu-reference.json.
  • data/ — JSON content: the default dive-setup.json and per-topic quiz-*.json exam banks.
  • locales/ — en.json, cs.json, es.json translation bundles.
  • css/ — single styles.css plus theme tokens; no preprocessor.
  • sandbox/ — sandbox entry points (index.html, tissue-saturation.html, transfilling.html, cascade-filling.html, gas-law.html).
  • icons/, fonts/, images/ — app icons (SVG), web fonts (Fraunces + Inter, WOFF2), images.
  • Top-level HTML files: landing (index.html), four theory lessons, seven quizzes, about.html.
  • CNAME — decotheory.eu.

Deployment

GitHub Pages from the main branch, served under the decotheory.eu custom domain configured via the CNAME file.

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