How to do "one page checkout" in shop-script 7 without a plugin?

Question

CMS

I know about a plugin that does this, but how do I do it manually? Do you have a link to some tutorial?

Answer 1

Just like everything else on the same page - using ajax. The link is my old code, which, in principle, works, but can be improved. Unfortunately, I can't share the new code.
https://jsfiddle.net/chelbeh/5m6ek0aw/