Object.prototype.toString( ) When the toString method is called, the following steps are taken:

1. Get the [[Class]] property of this object.
2. Compute a string value by concatenating the three strings “[object ", Result (1), and "]“.
3. Return Result (2)

So, with that out of the way, the best option we have to get an object's type is something like the following:

var getType = function(obj){
    return ({}.toString.call(obj)).replace('[Object ','').replace(']','');
    //.match(/^\[object\s(.*)\]$/)[1]
};

Is a solid, cross-browser implementation and cross frame safe.