Leonardo Devai
17a890cc08
Pinned 2026 toolchains (Go 1.26, Rust 1.98/edition 2024, Python 3.14 + uv, Node 24, Zig 0.16, NixOS 26.05), postgres 18 / mongo 8, lockfiles built from, non-root runtimes, .dockerignore, per-project LICENSE, READMEs with the git.devai.io clone line, checkout@v7 CI. Security fixes in the legacy Rust APIs (any-password login, self-assigned admin, hard-coded JWT secret), JWT alg/exp/sub enforcement across the blog series, safe markdown links in the frontends, and many smaller bugs — every project was built, run and exercised end to end. Adds scripts/publish.sh + a CI publish job that splits every folder into its own repo at git.devai.io/templates/<folder>. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01128fhuZbgivaSJvtMf4s1G
2.2 KiB
crypto-ticker
A little price board for Bitcoin, Ethereum and friends that refreshes itself every 30 seconds, with 24-hour changes in green and red. It teaches polling: asking an API again on a timer.
Run
Get it: git clone https://git.devai.io/templates/crypto-ticker.git
Double-click index.html — it opens in your browser and works, as long as
you're online (it calls the price API live). Nothing to install.
Or serve it like production:
docker compose up --build
Then open http://localhost:8080.
How it works
The API can't tell the page when prices change, so the page asks again on a timer:
refresh(); // once now…
setInterval(refresh, 30000); // …then every 30 seconds
Each refresh() is one ordinary fetch() to CoinGecko's free
/simple/price endpoint (no key needed) with the coin ids in the query string
and include_24hr_change=true. render() rebuilds one row per coin with
createElement and textContent, formats prices with Intl.NumberFormat
(extra decimals for coins under $1), and colors the change green ▲ or red
▼.
Polling a free API means you will sometimes be throttled. On a 429 ("too many requests") or a network error, the page keeps the last good prices on screen, says so, and simply tries again on the next tick. "Loading prices…" shows until the first answer arrives.
Try it: add a coin to COINS (e.g. cardano), poll every 60 seconds to be
gentler on the free tier, or add include_market_cap=true and show it.
Layout
index.html an empty rows box, a status line and "last updated"
app.js COINS, refresh(), render() and the interval
styles.css the look — green / red change colors; follows light or dark mode
Deploy
Push to your own GitHub repo and the shipped workflow
(.github/workflows/ci.yml) tests the compose stack, publishes the image to
GHCR, and — once you set the DEPLOY_HOST / DEPLOY_USER variables and
DEPLOY_KEY secret — deploys it to your server over ssh.
Part of devai.io — the APIs & Data track: fetch real data from the internet. Next up: dictionary-lookup.