parallel-merge.js

exports.handler = (event, context, callback) => {
   var output = {};
   event.forEach(function(obj) { output = mergeJSON(output, obj); });
   context.succeed(output);
};

var jsonC = {}.constructor;

var isJSON = function(json) {
   if (json && json.constructor === jsonC) {
       return true;
   } else {
       return false;
   }
}

var mergeJSON = function(json1, json2) {
   var result = null;
   if (isJSON(json2)) {
       result = {};
       if (isJSON(json1)) {
           for (var key in json1) {
               result[key] = json1[key];
           }
       }

       for (var key in json2) {
           if (typeof result[key] === “object” && typeof json2 === “object”) {
               result[key] = mergeJSON(result[key], json2[key]);
           } else {
               result[key] = json2[key];
           }
       }
   } else if (Array.isArray(json1) && Array.isArray(json2)) {
       result = json1;

       for (var i = 0; i < json2.length; i++) {
           if (result.indexOf(json2[i]) === -1) {
               result[result.length] = json2[i];
           }
       }
   } else {
       result = json2;
   }

   return result;
}