in case of processing a very large array e.g. Promise.all(A_VERY_LARGE_ARRAY_OF_XHR_PROMISE)
which would probably blow you browser memory by trying to send all requests at the same time
solution is limit the concurrent of requests, and wrap promise in thunk
Promise.allConcurrent(2)([()=>fetch('BLAH1'), ()=>fetch('BLAH2'),...()=>fetch('BLAHN')])