javascript

CHAPTER 5 ■ MEMBER INHERITANCE
162
Now let’s add four chopped Heath Bars to VanillaBean.prototype in order to change vanilla to Ben
& Jerry’s Vanilla Heath Bar Crunch and coffee to Ben & Jerry’ Coffee Heath Bar Crunch. However, as
Figure 5–11 displays, by doing so we also wind up with Chocolate Heath Bar Crunch and Mint Chocolate
Chip Heath Bar Crunch, because everything that inherits from VanillaBean gets the heathBars member!
var VanillaBean = function(vanilla, cinnamon) {
this.vanilla = [1, "bean", vanilla ? vanilla : "Madagascar Bourbon"];
cinnamon && (this.cinnamon = [1, "stick", "Saigon"]);
};
VanillaBean.prototype = {
heavyCream: [1, "cup", "Organic Valley"],
halfHalf: [2, "cup", "Organic Valley"],
sugar: [5/8, "cup"],
yolks: [6]
};
var Coffee = function(coffee) {
this.coffee = coffee || [1/4, "cup, coarsely ground", "Starbucks Espresso"];
};
Coffee.prototype = new VanillaBean();
var Chocolate = function(cocoa, bittersweet) {
this.cocoa = cocoa || [3/16, "cup", "Callebaut"];
this.bittersweet = bittersweet || [1 + 1/2, "cup", "Callebaut"];
};
Chocolate.prototype = new VanillaBean();
Chocolate.prototype.yolks = [4];
var MintChocolateChunk = function(mint) {
this.mint = mint || [1, "cup", "fresh mint leaves"];
};
MintChocolateChunk.prototype = new Chocolate();
MintChocolateChunk.prototype.vanilla = [1/3, "bean", "Madagascar Bourbon"];
MintChocolateChunk.prototype.bittersweet[0] = 1;
delete MintChocolateChunk.prototype.cocoa;
var vanilla = new VanillaBean();
var coffee = new Coffee();
var chocolate = new Chocolate();
var mintChocolateChunk = new MintChocolateChunk();
VanillaBean.prototype.heathBars = [4, "Heath Bars, chopped in chunks"];
console.dir(vanilla);
console.dir(coffee);
console.dir(chocolate);
console.dir(mintChocolateChunk);