オブジェクトのプロパティ

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);

//表示結果
Object { type: "Dot syntax", date created: "String with space", myString: "String value", 0.806938221617259: "Random Number", [object Object]: "Object", : "Even an empty string" }