I think something like rollup's online repl would be very convenient for playing with esbuild, which also could demonstrate the real power of using esbuild to build an unversal bundler for browser|node( webassembly support, bundle on the web, using plugin to load bare module from http & unpkg and build real web application using esbuild it self so on)。 I don't know are you intersting to do this, if you do I can do some help.