プロパティの巡回

function showProps(obj, objName) {
  var result = "";
  for (var i in obj) {
    if (obj.hasOwnProperty(i)) {
        result += objName + "." + i + " = " + obj[i] + "\n";
    }
  }
  return result;
}

var myCar = new Object();
myCar["make"] = "Ford";
myCar["model"] = "Mustang";
myCar["year"] = 1969;

console.log(showProps(myCar, "myCar"));

//出力結果
myCar.make = Ford
myCar.model = Mustang
myCar.year = 1969