promise-loop.js

let total = 0;

const processChunk = function(chunkList, chunkIndex) {
  const chunk = chunkList[chunkIndex];  
  
  // do stuff with chunk asynchronously
  return doStuff(chunk)
    .then((result) => {
      if (chunkIndex < chunkList.length) {
        total += result;        
        // Process the next chunk.
        return processChunk(chunkList, chunkIndex+1);
      } else {
        // Done
        return totalResult;
      }
    });  
};

const chunks = getArrayOfStuffToProcess();
const serialised = processChunk(chunks, 0);