Neither of these cases are more readable, if you want a readable swap can you get better than:

  const [newA,newB]=swap(b,a);

It does look a lot like linq, and has the same hidden complexity problem of linq.. while C# went through extreme lengths to optimise the performance penalties down to almost negligible - JS isn't there yet (and may never be after requiring multiple engines to catch up). An individual function in a chain of drop/jump/take/filter/change(map)/cast steps cannot look ahead to future needs, nor re-order for better efficiency... a (good) software engineer can. In the same way there's good ways to write SQL (benefit from indexes and reduce the set quickly) and bad (cause full table scans).