Better promise constructs

promiseGoodPractice.js

function ExampleAPIHandler(downChainResponse, otherdata, next) {
  var promiseArray = [];
  var respJSON = {
      body: {},
      success: true,
      warnings: [],
      errors: []
      };
      
  promiseArray.push(processingStep1(downChainResponse.body.schemes));
  promiseArray.push(processingStep2(downChainResponse.body.schemes,userId));
  
   // Need to aggregate the data for the front end.
  return Promise.all(promiseArray)
  
  // Example of Bad
  .then(function (resultArray) {
    if (!resultArray || resultArray.length == 0) {
        throw new Error('Error in executing processSchemesNode and processFileLockedStatus');
    }
    // Aggregate responses - return the updated schemes
    return aggregateSchemesAndLockStatus(resultArray);
  })
  // Example of better
  .then(aggregateSchemesAndLockStatus) // Just call a named function and do any checking in that function
  .catch(handleCatch)
}

function aggregateSchemesAndLockStatus(resultArray) {
  // Check here and allow parent catch to catch
  if (!resultArray || resultArray.length == 0) {
        throw new Error('Error in aggregating data');
    }
}