Introduction
Differential Inheritance is a common prototype-oriented model that uses the concept that most objects are derived from other, more generic objects, and only differ in a few small aspects. Each object maintains a reference to its prototype and a table of properties that are different.
Example
The following code provides a simple method for "inherit" an object:
Object.prototype.inherit = function(){
// Create a new object with this as its prototype
var p = Object.create(this);
/* actually not necessary:
// Apply the constructor on the new object
this.constructor.apply(p, arguments);
*/
return p;
};
Using inherit, it becomes possible to simply derive more specific objects from a generic prototype. The following is a simple example of building up increasingly more specific objects using the inherit method and differential inheritance.
var root = {}; // Could be any object with any prototype object
var record = root.inherit();
record.toString = function(){ return "a Record"; };
var person = root.inherit();
person.firstName = false;
person.lastName = false;
person.toString = function(){
return this.firstName ?
(this.lastName ?
this.firstName + " " +this.lastName :
this.firstName) :
(this.lastName ?
this.lastName :
"a Person");
};
JoePerson = person.inherit();
JoePerson.firstName = "Joe";
alert( JoePerson.toString() );