@dancing-ninjas/project-euler-helper-kit

Math helpers & a tiny CLI for Project Euler–style problems, tailored for Dancing Ninjas, plus telemetry strategies that work under npmjs.org‑only egress.

⚠️ Exact per‑download timestamps from the public npm registry are only available from logs at the network boundary (e.g., your corporate proxy/firewall) because package code runs after download. This kit includes a parser to extract those timestamps from your own logs. A secondary (install‑time) signal uses a single GET to registry.npmjs.org so it also complies with your constraint.

Quick start (helpers & CLI)

npm i
npm run build

npx ./bin/euler-cli.js list
npx ./bin/euler-cli.js prime 1000003
npx ./bin/euler-cli.js nCr 40 20

Telemetry under npmjs.org‑only constraint

You have two complementary strategies:

1) Primary (recommended): parse your proxy logs → exact download timestamps

Your proxy/egress firewall already logs requests to registry.npmjs.org. Every tarball download hits a path like:

/@dancing-ninjas%2Fproject-euler-helper-kit/-/project-euler-helper-kit-1.0.0.tgz

Use the included script to convert those log lines into normalized NDJSON events.

Example (Nginx‑style access logs):

node scripts/npmjs-proxy-logs-to-events.mjs   --in /var/log/proxy/access.log   --out telemetry/events.ndjson   --pkg @dancing-ninjas/project-euler-helper-kit

Each event:

{{"kind":"download","at":"2025-09-04T12:34:56Z","pkg":"@dancing-ninjas/project-euler-helper-kit","http":{{"path":"/@dancing-ninjas%2Fproject-euler-helper-kit/-/project-euler-helper-kit-1.0.0.tgz","status":200,"ua":"npm/10 node/v20 ..."}}}}

2) Optional (install‑time) signal to npmjs.org

Enable a small postinstall script that performs one GET to https://registry.npmjs.org/-/ping?dn_sig=<base64url> and also appends the same signal to the User‑Agent. Your proxy logs will capture the timestamp.

Enable by setting:

export DN_TELEMETRY_MODE=npm-ping   # off by default
npm i @dancing-ninjas/[email protected]

The signal is compact and includes: {{ pkg, version, at, node, platform, arch, projectHash }}. No external endpoints other than npmjs.org are contacted. Network errors are ignored and the install never fails because of telemetry.

This captures install time (very close to download in practice), not the exact download moment.

Library API (snapshot)

import {{
  isPrime, primesUpTo, primeFactors,
  gcd, lcm, modPow, modInverse,
  factorialBig, nCrBig,
  divisors, properDivisors,
  permutations, combinations,
  fibonacciBig, sumDigits, digits, isPalindrome, collatzLength
}} from '@dancing-ninjas/project-euler-helper-kit';

Security & privacy

• Telemetry is off by default. Opt in by setting DN_TELEMETRY_MODE=npm-ping.
• No PII is sent; only a hash of the project path (projectHash) is included.
• The request goes to registry.npmjs.org and is intended purely for your own proxy logs.
• For exact download times, rely on your proxy logs (strategy 1).

License

MIT © Dancing Ninjas