js....

function Animal( objectName ) {
    this._name = objectName;
}
Animal.prototype._name = "Animal’s prototype.";
Animal.prototype.makeNoise = function () { console.log( this._name + ' is silent.' ); };
Animal.prototype.run = function () { console.log( this._name + ' runs.' ); };

var a = new Animal( "Basic Animal." );
a.makeNoise();


function Dog( objectName ) {
    this._name = objectName;
}
Dog.prototype = new Animal( "Dog’s prototype." );
Dog.prototype.makeNoise = function () { console.log( this._name + ' is barking.' ); };

//var pAnimal = Animal.prototype;
//delete pAnimal.run;
delete Animal.prototype.run;
//Animal.prototype = Dog.prototype;

var m = new Dog( "Médor" );

m.makeNoise();
m.run();