Training Guide: Programming in HTML5 with JavaScript and CSS3 Ebook

Lesson 1: Creating JavaScript objects CHAPTER 6 281

This completes Car, and Boat is similar except that Boat has a propellerBladeQuantity,

which is initialized to three, instead of the wheelQuantity property. In addition, getInfo

returns the vehicle type of Boat and calls the Vehicle getInfo method as follows.

var Boat = (function (parent) {

Boat.prototype = new Vehicle();

Boat.prototype.constructor = Boat;

function Boat(year, make, model) {

parent.call(this, year, make, model);

this.propellerBladeQuantity = 3;

}

Boat.prototype.getInfo = function () {

return 'Vehicle Type: Boat ' + parent.prototype.getInfo.call(this);

};

return Boat;

})(Vehicle);

In addition to the Vehicle tests already presented, you need to verify the following for the

child classes.

■■Car and Boat have the inherited year, make, and model properties.

■■Car has its wheelQuantity property and it's set.

■■Boat has its propellerBladeQuantity and it's set.

■■Car and Boat return the proper value from the replaced getInfo method.

■■Car and Boat return the proper value from the inherited startEngine method.

The following are the Car and Boat tests.

test('Car Inheritance Test', function () {

expect(6);

var c = new Car(2012, 'Toyota', 'Rav4');

var actual = c.year;

var expected = 2012;

equal(actual, expected, 'Expected value: ' + expected +

' Actual value: ' + actual);

var actual = c.make;

var expected = 'Toyota';

equal(actual, expected, 'Expected value: ' + expected +

' Actual value: ' + actual);

var actual = c.model;

var expected = 'Rav4';

equal(actual, expected, 'Expected value: ' + expected +

' Actual value: ' + actual);

var actual = c.wheelQuantity;

var expected = 4;

equal(actual, expected, 'Expected value: ' + expected +

' Actual value: ' + actual);

var actual = c.getInfo();

var expected = 'Vehicle Type: Car 2012 Toyota Rav4';

equal(actual, expected, 'Expected value: ' + expected +

' Actual value: ' + actual);