JSON is a very lightweight text serialization that can closely resemble your in-memory object structure. By Contrast XML support way more methods of serialization that are more complex and/or less clear in practice.
They could use a different file extension and even gzip the file as well. I often use line separated JSON+GZ as an interchange format for records.
The blurriness is a problem… With the pdf library I’m using (jsPDF) I cannot export the SVG directly so I convert it to an image and then embed the image in the pdf.
To solve the problem, I can increase the converted image’s resolution but then the pdf becomes huge (~20 MB, for example). There is a ‘quality’ parameter in the code, maybe I’ll expose it in the UI and you can find an optimum value.
I’ll try to find a way to export or ‘write’ the svg data directly in the pdf, I think it’s the best way to do it.
I don't think it's common to start a new project with both jQuery and React, or actively develop jQuery and React modules in the same project, but it is probably quite common for projects that initially used jQuery to gradually move modules to React.
It's possible. It's not something you normally intend to do in a new project but it's possible to use jQuery and other libraries inside React and it's handy when working with legacy code.
FYI, I just shared your project on Product Hunt: https://www.producthunt.com/posts/printable-mockups
I think the design community there will find it really useful!