It's a bit of work for a typical Swing app using this technology (TeaVM) which has a small runtime. However, there is another Java-to-JS compiler called CheerpJ

It's a bit of work for a typical Swing app using this technology (TeaVM) which has a small runtime. However, there is another Java-to-JS compiler called CheerpJ which handles many Swing apps without much work. The only downside is a larger runtime, so apps can take a bit to launch. I'd love to hear more about your idea for web based ireport. Send me a note at jeff at reportmill if you want to chat (or call the main line).