this.hoge; // <- getter ? setter? set: function(val) {this._piyo = val} // is this piyo affected to original object?

setter test

/* see if just "obj.hoge" is setter or getter */
var obj = {};
Object.defineProperty(obj, 'hoge', {
  get: function(){console.log("get")},
  set: function(){console.log("set")}
});

obj.hoge;


/* see if this._hoge is readable / writable */
var fuga = {};
Object.defineProperty(obj, 'piyo', {
  get: function(){return this._piyo},
  set: function(val){this._piyo = val} // this._piyo is hidden!!!
});

console.log(fuga.piyo);
console.log(fuga._piyo);
console.log(fuga);

fuga.piyo = "shinout";
console.log(fuga.piyo);
console.log(fuga._piyo);
console.log(fuga);


fuga._piyo = "fu-ga";
console.log(fuga.piyo);
console.log(fuga._piyo);
console.log(fuga);