javascript 連想配列

https://developer.mozilla.org/ja/docs/Web/JavaScript/Guide/Working_with_Objects

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

myCar["make"] = "Ford";
myCar["model"] = "Mustang";
myCar["year"] = 1969;

var myObj = new Object(),
    str = "myString",
    rand = Math.random(),
    obj = new Object();

myObj.type              = "Dot syntax";
myObj["date created"]   = "String with space";
myObj[str]              = "String value";
myObj[rand]             = "Random Number";
myObj[obj]              = "Object";
myObj[""]               = "Even an empty string";

console.log(myObj);