using dot notation with more than one in javascript syntax

Question

Could you please explain whats the mean of
first[dot]second like declaration in javascript rules

first.second = (function () {
    //...
})();

Answer 1

it means first is an object and second is a property of that object.

it can be defined as follows too;

var first = {};// {} -is JS object notation
first.second = function(){
   alert('test');
};

//or
var first = {
  second : function(){
     alert('test');
  }
};


//invoke the function
first.second();// prompt alert message

simple documentation