JSON A:
{
"Field A":"1",
"Field B":"2",
"Field D":"Something",
"Field E":"6"
}

JSON B:
{
"Field A":"1",
"Field B":"2",
"Field C":"3",
"Field D":"Different"
}

{
"Field C":"3", // because function sees jsonstringB had no "Field C"
"Field D": "Different" // sees jsonstringB had a different value for "Field D"
}

var compareJSON = function(obj1, obj2) {
  var ret = {};
  for(var i in obj2) {
    if(!obj1.hasOwnProperty(i) || obj2[i] !== obj1[i]) {
      ret[i] = obj2[i];
    }
  }
  return ret;
};

isEmpty

var compareObj = function(obj1, obj2) {
  var ret = {},rett;
  for(var i in obj2) {
      rett = {};
      if (typeof obj2[i] === 'object'){
          rett = compareObj (obj1[i], obj2[i]) ;
          if (!isEmpty(rett) ){
           ret[i]= rett
          }
       }else{
           if(!obj1 || !obj1.hasOwnProperty(i) || obj2[i] !== obj1[i]) {
              ret[i] = obj2[i];
      }
   }
  }
  return ret;
};

var compareJSON = function(obj1, obj2) {
      var ret = {};
      for(var i in obj2) {
        if(!obj1.hasOwnProperty(i) || obj2[i] !== obj1[i]) {
          if(!Array.isArray(obj2[i]) || !(JSON.stringify(obj2[i]) == JSON.stringify(obj1[i]))){
          ret[i] = obj2[i];
          }
        }
      }
      return ret;
    };