Mastering JavaScript

Chapter 4
//Both these functions share the common 'Player.prototype.
wearsGlasses' variable
cricketer.fixEyes();
golfer.fixEyes();
cricketer.endorses="Other Brand";//public variable can be updated
//Both Player's public method is now changed via their prototype
Player.prototype.fixEyes=function(){
this.wearGlasses=true;
};
//Only Cricketer's function is changed
cricketer.switchHands=function(){
this.batPreference="undecided";
};
})();
Let's understand a few important concepts from this example:
• The retirementAge variable is a private variable that has no privileged
method to get or set its value.
• The country variable is a private variable created as a constructor argument.
Constructor arguments are available as private variables to the object.
• When we called cricketer.switchHands(), it was only applied to the
cricketer and not to both the players, although it's a prototype function of
the Player itself.
• Private functions and privileged methods are instantiated with each new
object created. In our example, new copies of isAvailable() and book()
would be created for each new player instance that we create. On the other
hand, only one copy of public methods is created and shared between all
instances. This can mean a bit of performance gain. If you don't really need to
make something private, think about keeping it public.
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