Prototype defines a property that is shared by all objects of the specified type.
Syntax:
objectType.prototype.propertyName = value
Parameters:
objectType - the name of a constructor or function specifying an object type.
propertyName - the name of the property to be created.
value - the property value initially assigned for all objects of the specified objectType.
Prototype can be applied to any object created with new operator - user-defined objects or standard javascript objects like Array, Date, String, Number, etc.
Here's an example from original Netscape's javascript documentstion:
var today = new Date()
var birthday = new Date(95,12,17)
Date.prototype.description=null
today.description="Oh what a beautiful mornin\'"
birthday.description="The day you were born"
After you set a property for the prototype, all subsequent objects created with Date() will have the property:
startDate=new Date()
startDate.description="Started the daily grind"
Hope it will help you.
good luck