see http://www.w3schools.com/js/js_objects.asp
I'm reading your tutorial and came across the following. It appears to be wrong and contradicts the examples.
Example1person.lastName;
Example2person["lastName"];
Accessing Object PropertiesYou can access object properties in two ways:
objectName.propertyName()
or
objectName[propertyName()]
Shouldn't this be:
objectName.propertyName
and
objectName["propertyName"]
respectively?