Cosmos DB - queryIterator + request unit charge

query.js

      var queryIterator = client.queryDocuments(collection._self, querySpec);
      queryIterator.executeNext(function (err, results, headers) {
        if (err) {
          // deal with error...
        } else {
          // deal with payload...
          var ruConsumed = headers['x-ms-request-charge'];
        }
      })
      return queryIterator.toArray( (e, r) => {
        if(e) {
          reject(e)
        } else {
          resolve(r)
        }
      })