# Deploy a static JavaScript regex playground on Yeeted

The **cold-start canary**: zero dependencies, no build step, bare
`index.html` + one ES module - the platform's simplest static path. If this
sample deploys slowly, the platform is slow; nothing else can be blamed.

Logic lives in `src/matcher.js` (pure, DOM-free) so `node --test
test/matcher.test.js` covers it - including the XSS-escape property and
zero-width-pattern termination. `smoke.sh <url>` checks a deployment.

## Run locally

From `static/regex-vanilla`, use Node.js for the pure logic tests and Python
for a local static server:

```sh
node --test test/matcher.test.js
python3 -m http.server 8000
```

Open `http://localhost:8000`; serving over HTTP allows the browser to load
the JavaScript module. Try `cat` against `cat catalog` and inspect the
highlighted matches. Invalid patterns display an error.

## Deploy and verify

Follow the [deployment walkthrough](getting-started.md). Upload this
folder's `index.html` and `src/matcher.js` together. No database, package
installation, Dockerfile, or build command is required.

```sh
sh smoke.sh "$PREVIEW_URL"
```

The deployed smoke script checks the static resources. The Node tests cover
matching, flag normalization, escaped output, and stopping on a zero-width
match. Open the page to verify the full browser interaction separately.

## What to change before real use

Matching runs on the browser's main thread. A pathological regular expression
can block the tab; there is no worker timeout or complexity limit. Zero-width
matches stop the loop rather than being counted like ordinary matches. These
are deliberate limits of the small demo, not a complete regex workbench.

[All examples](index.md) · [Deploy an example](getting-started.md)