How to get the object type in javascript:

var obj = {}; // any object

1. typeof:

typeof obj; // object
2. instanceof:

obj instanceof Object; // true
3. Object.prototype.toString:

Object.prototype.toString.call(obj); // [object Object]
4. constructor:

obj.constructor // Object
5. Duck:

typeof obj === "object" && "hasOwnProperty" in obj && "toString" in obj; // true

Reference Material: http://www.iteye.com/topic/318821