我有一些示例代码来自Glen Johnson的书籍使用JavaScript和CSS3编写的HTML5 。
我的“应用代码”如下:
// Demo of how implementing inheritance works
var Vehicle = (function () {
function Vehicle(year, make, model) {
this.year = year;
this.make = make;
this.model = model;
}
Vehicle.prototype.getInfo = function () {
return this.year + ' ' + this.make + ' ' + this.model;
};
Vehicle.prototype.startEngine = function () {
return 'Vroom';
};
return Vehicle;
})();
var Car = (function (parent) {
Car.prototype = new Vehicle();
Car.prototype.constructor = Car;
function Car(year, make, model) {
this.wheelQuantity = 4;
parent.call(this, year, make, model);
}
Car.prototype.getInfo = function () {
return 'Vehicle Type: Car ' + parent.prototype.getInfo.call(this);
};
return Car;
})(Vehicle);
var Boat = (function (parent) {
Boat.prototype = new Vehicle();
Boat.prototype.constructor = Boat;
function Boat(year, make, model) {
this.propellerBladeQuality = 3;
parent.call(this, year, make, model);
}
Boat.prototype.getInfo = function() {
return 'Vehicle Type: Boat' + parent.prototype.getInfo.call(this);
}
})(Vehicle);
我的测试如下:
module("Implementing Inheritance", {});
test('Creating a Vehicle', function () {
expect(2);
var actual,
expected,
v = new Vehicle(2012, 'Toyota', 'Rav4');
actual = v.getInfo();
expected = '2012 Toyota Rav4';
equal(expected, actual);
actual = v.startEngine();
expected = 'Vroom';
equal(expected, actual);
});
test('Create a Car', function () {
expect(5);
var expectedYear = 2012,
expectedMake = 'Toyota',
expectedModel = 'Rav4',
c = new Car(expectedYear, expectedMake, expectedModel);
equal(c.year, expectedYear, 'Year');
equal(c.make, expectedMake, 'Make');
equal(c.model, expectedModel, 'Model');
equal(c.wheelQuantity, 4, 'wheelQuality');
equal(c.getInfo(), 'Vehicle Type: Car ' + expectedYear + ' ' + expectedMake + ' ' + expectedModel, 'getInfo()');
});
test('Create a Boat', function () {
expect(5);
var expectedYear = 12334,
expectedMake = 'dummy-make',
expectedModel = 'dummy-model',
expectedPropellerBladeQuality = 3,
b = new Boat(expectedYear, expectedMake, expectedModel);
equal(b.year, expectedYear, 'Year');
equal(b.make, expectedMake, 'Make');
equal(b.model, expectedModel, 'Model');
equal(b.propellerBladeQuality, expectedPropellerBladeQuality, 'propellerBladeQuality');
equal(b.getInfo(), 'Vehicle Type: Boat ' + expectedYear + ' ' + expectedMake + ' ' + expectedModel, 'getInfo()');
});
当它们运行时,创建一个汽车测试通过,但创建一个船测试失败,但有以下异常:
Died on test #1 at file:///C://JavaScript_Samples/tests/implementingInheritance.js:33:1: undefined is not a function
Source:
TypeError: undefined is not a function
at Object.<anonymous> (file:///C:/JavaScript_Samples/tests/implementingInheritance.js:40:13)
我看不出原因,Car
和Boat
的代码似乎与我相同。
我在Chrome和Firefox中尝试了这一点,两者的结果相同。
有任何建议吗?
答案 0 :(得分:1)
您缺少创建的return
类的Boat
语句:
var Boat = (function (parent) {
Boat.prototype = new Vehicle();
Boat.prototype.constructor = Boat;
function Boat(year, make, model) {
this.propellerBladeQuality = 3;
parent.call(this, year, make, model);
}
Boat.prototype.getInfo = function() {
return 'Vehicle Type: Boat' + parent.prototype.getInfo.call(this);
}
// insert return statement here
return Boat;
})(Vehicle);