onchange

var record = input.records[0]

var persistentMap = typeof(persistentMap) === 'undefined' ? {} : persistentMap;
var valuesToSend = {};
var timestamps = {};
var outRecord = newWireRecord();

//called with every property and its value
function process(key,value) {
    if(key.endsWith("_timestamp")){
      //store timestamps in temporary map
      timestamps[key] = value;
      return;
    }
    var oldValue = persistentMap[key];
    if(oldValue != undefined && oldValue != value.getValue()){
      valuesToSend[key] = value;
    }
    persistentMap[key] = value.getValue();
}

function traverse(o,func) {
    for (var i in o) {
        func.apply(this,[i,o[i]]);
        if (o[i] !== null && typeof(o[i])=="object") {
            //going one step down in the object tree!!
            traverse(o[i],func);
        }
    }
}

traverse(record, process);

if(Object.keys(valuesToSend).length > 0){
  traverse(valuesToSend, addToOutput);
  output.add(outRecord);
}

function addToOutput(key, value) {
  outRecord[key] = value;
  //retrieve previously stored timestamp if present
  if(timestamps[key+"_timestamp"] != undefined){
    outRecord[key+"_timestamp"]=timestamps[key+"_timestamp"];
  }
}