Thank you!

Thank you for mentionig this. There are still some caveats I hope fix soon. And I working on a plugin system to allow user modify all aspects of the capture

Yes, the default capture output is a svg dataurl. But there many other export options. This lib was made as an internal tool for another project called Zumly that is zoomable engine and the svg format was the faster output I found. But then I realized that could be an independent tool like html2canvas

It seems like it would be a lot more efficient to use SVG for screenshot testing design system components rather than raster images.

I'm using several functions to clone the DOM and insert it into an SVG <foreignObject>. This approach is now well supported across modern browsers, although <foreignObject> is still a rather primitive way to handle HTML and styles within SVG, which can sometimes lead to results that aren't fully precise in certain cases. To reduce the size, I created internal CSS classes to avoid repeating CSS properties, and I'm also using several caches to prevent re-cloning styles that have already been processed. There's still a long journey ahead, but I hope a plugin system will allow for more fine-grained control over all capture stages

Yes, I'm afraid it depends a lot on what elements you are capturing. But maybe with a plugin designed to perform a capture burst and collect them in an array, it would be possible to generate an animation as output.