If I were reviewing a system design, yes, with js, I'd still like a sequence diagram. I'd just indicate that ordering may not be exact between certain bands of

If I were reviewing a system design, yes, with js, I'd still like a sequence diagram. I'd just indicate that ordering may not be exact between certain bands of requests. I model concurrent systems all the time in sequence (ish) diagrams. I want to know that action X will trigger N calls and those calls call service foo and bar, and that foo then calls out to its data store and eventually returns something and service bar calls services raz and quux and those each fist call a caching service before going to their data stores. All requests eventually return (in the happy path). Now, as a reviewer, I can quickly see what talks to what and why that call happens and I can ask more intelligent questions like what happens if a cache hit happens when the data store has been updated. What do you prefer?