Exactly. I love shipping features for customers—I generally can't do this without bouncing from JavaScript to Ruby to back again faster than I could say "I'm working in this specific context right now."

For example, today I added drag + drop image upload that posts directly to S3, but not without resizing the file to maximum dimensions of 800 x 600 first, and finally kicking off a Sidekiq job to generate all of the smaller thumbnails. Hard to say whether that was more front-end or back-end code.