6.s092 Client-Side Code Checker

A browser-based port of the 6.s092 catsoop problem set autograder. Everything runs client-side — no server needed for Python execution. Python code runs via Pyodide (Python compiled to WebAssembly).

Features

• All question types from catsoop: multiple choice (checkbox/radio/dropdown), expression, python literal, small box, number, multiexpression, python code
• Python execution in browser via Pyodide + WebAssembly
• KaTeX rendering for math
• CodeMirror editor for coding questions
• Progress stored in IndexedDB — persists across sessions, no login needed
• Answer restoration — typed answers and code survive page refresh

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Quick start

git clone <repo-url>
cd 6s079
python3 -m http.server 8080
# open http://localhost:8080/app/

The server must be started from the repo root so that both app/ and 6s092/courses/ are accessible.

Other local server options

# Node
npx serve .
# → http://localhost:3000/app/

# VS Code: right-click app/index.html → "Open with Live Server"
#   (must set Live Server root to the repo root, not app/)

---

Deploying as a static website

No build step is required — the repo is the website.

GitHub Pages

1. Push this repo to GitHub.
2. Go to Settings → Pages.
3. Source: GitHub Actions.
4. The workflow at .github/workflows/deploy.yml runs automatically on every push to main.
5. The site will be live at https://<user>.github.io/<repo>/app/.

The root URL (https://<user>.github.io/<repo>/) redirects to /app/ via the _redirects file (honoured by GitHub Pages via the Actions workflow).

Cloudflare Pages

1. Connect the repo in the Cloudflare Pages dashboard.
2. Build command: (leave empty)
3. Build output directory: . (a single dot — the repo root)
4. Deploy. Cloudflare reads _redirects and netlify.toml automatically, so / redirects to /app/.

Netlify

1. Connect the repo in the Netlify dashboard.
2. Build command: (leave empty)
3. Publish directory: .
4. netlify.toml in the repo root handles the / → /app/ redirect.

GitLab Pages

Push the repo to GitLab. .gitlab-ci.yml copies the repo root into the public/ directory that GitLab Pages requires. The site is served at https://<namespace>.gitlab.io/<repo>/app/.

---

Repository layout

app/
  index.html          — SPA shell (CDN deps: Pyodide, KaTeX, marked, CodeMirror, idb)
  style.css           — all styles
  manifest.json       — list of courses + PSets (auto-generated)
  js/
    app.js            — routing + page rendering
    parser.js         — parse content.md → segments
    py-runner.js      — Pyodide wrapper + Python env setup
    questions.js      — question type renderers + checkers
    storage.js        — IndexedDB (scores + saved code)

6s092/courses/        — original course content (served as static files)
  IAP19/PS/PS01/content.md
  ...

tests/                — Node.js unit tests (run with `node tests/*.mjs`)
_redirects            — Cloudflare/Netlify SPA redirect rule
netlify.toml          — Netlify build + redirect config
.github/workflows/    — GitHub Actions deployment
.gitlab-ci.yml        — GitLab Pages deployment

---

Regenerating the manifest

If you add new problem sets:

python3 -c "
import os, json
courses_root = '6s092/courses'
manifest = {'courses': []}
for course_id in sorted(os.listdir(courses_root)):
    course_dir = os.path.join(courses_root, course_id)
    if not os.path.isdir(course_dir): continue
    if course_id.startswith('testing'): continue
    ps_dir = os.path.join(course_dir, 'PS')
    psets = []
    if os.path.isdir(ps_dir):
        for ps in sorted(os.listdir(ps_dir)):
            if os.path.isdir(os.path.join(ps_dir, ps)) and not ps.startswith('.'):
                psets.append(ps)
    manifest['courses'].append({'id': course_id, 'name': course_id, 'psets': psets})
with open('app/manifest.json', 'w') as f:
    json.dump(manifest, f, indent=2)
print('manifest.json updated')
"

---

Running the tests

node tests/syntax-check.mjs   # JS syntax + nullish coalescing precedence
node tests/parser.test.mjs    # content.md parser
node tests/questions.test.mjs # question renderers + expression normalizer

---

Compatibility notes

• <python> blocks that use cs_print() are fully supported
• csq_funcs (custom functions for expression questions) are picked up from preload.py execution
• tutor.init_random() seeds randomness per page path
• Admin/grade-related code from preload.py is silently ignored
• Pyodide loads ~10 MB on first visit; subsequent visits are fast (browser-cached)

A browser-based port of the 6.s092 catsoop problem set autograder. Everything runs client-side — no server needed for Python execution. Python code runs via Pyodide (Python compiled to WebAssembly).

Features

• All question types from catsoop: multiple choice (checkbox/radio/dropdown), expression, python literal, small box, number, multiexpression, python code
• Python execution in browser via Pyodide + WebAssembly
• KaTeX rendering for math
• CodeMirror editor for coding questions
• Progress stored in IndexedDB — persists across sessions, no login needed

Running locally

You need a local HTTP server (due to fetch() CORS restrictions). Any of these work:

# Option 1 — Python (simplest)
cd /path/to/6s079        # the PARENT of the app/ folder
python3 -m http.server 8080
# then open http://localhost:8080/app/

# Option 2 — Node (npx serve)
npx serve .
# then open http://localhost:3000/app/

# Option 3 — VS Code Live Server extension
# Right-click app/index.html → "Open with Live Server"

The server must be started from the parent directory (6s079/) so that both app/ and 6s092/courses/ are reachable.

Architecture

app/
  index.html          — SPA shell (CDN deps: Pyodide, KaTeX, marked, CodeMirror, idb)
  style.css           — all styles
  manifest.json       — list of courses + PSets (auto-generated)
  js/
    app.js            — routing + page rendering
    parser.js         — parse content.md → segments
    py-runner.js      — Pyodide wrapper + Python env setup
    questions.js      — question type renderers + checkers
    storage.js        — IndexedDB (scores + saved code)

6s092/courses/        — original course content (unchanged)
  IAP19/PS/PS01/content.md
  ...

Regenerating the manifest

If you add new problem sets:

cd /path/to/6s079
python3 -c "
import os, json
courses_root = '6s092/courses'
manifest = {'courses': []}
for course_id in sorted(os.listdir(courses_root)):
    course_dir = os.path.join(courses_root, course_id)
    if not os.path.isdir(course_dir): continue
    if course_id.startswith('testing'): continue
    ps_dir = os.path.join(course_dir, 'PS')
    psets = []
    if os.path.isdir(ps_dir):
        for ps in sorted(os.listdir(ps_dir)):
            if os.path.isdir(os.path.join(ps_dir, ps)) and not ps.startswith('.'):
                psets.append(ps)
    manifest['courses'].append({'id': course_id, 'name': course_id, 'psets': psets})
with open('app/manifest.json', 'w') as f:
    json.dump(manifest, f, indent=2)
"

Notes on compatibility

• <python> blocks that use cs_print() are fully supported
• csq_funcs (custom functions for expression questions) are picked up from preload.py execution
• tutor.init_random() seeds randomness per page path
• Admin/grade-related code from preload.py is silently ignored (those features aren't ported)
• Pyodide loads ~10MB on first visit; subsequent visits are fast (cached by browser)