Alternatively, you can install JS Paint as a PWA (Progressive Web App),
but this does not yet support offline use
(as it doesn't include a Service Worker).
It's more like a bookmark (for now), except it runs in a special window.
The user interface for installing PWAs differs by browser and operating system.
On most desktop browsers, the install prompt is in the URL bar.
On mobile, the install prompt is generally found in the menu of browser options.
See
Installing PWAs for visual guidance.
Feel free to copy these to your site!
Some of them are rubbish, but a few of them I'm quite happy with.
Right click on the image and select "Save image as..." to download it,
then copy and paste the HTML code below it into your site,
and update the src attribute to point to where you're hosting the image.
Here are some buttons I collected
I don't know where most of these came from, and I've repurposed some of them.