//検証用コード
var key="author.modname.keyname";
var data = 0;
function chatHook(str){
 data = str;
}
function attackHook(a,v){
 if(getCarriedItem()==280){
  var ExtraData = Entity.getExtraData(v,key);
  clientMessage("ExtraDataの型は"+Object.prototype.toString.call(ExtraData));
  clientMessage("ExtraDataの中身は"+ExtraData);
  preventDefault();
 }else if(getCarriedItem()==281){
  var a = Entity.setExtraData(v, key, data);
  clientMessage("Entity.setExtraDataの戻り値の型は"+Object.prototype.toString.call(a));
  clientMessage("Entity.setExtraDataの戻り値は"+a);
  preventDefault();
 }
}