Question

通过将参数传递给构造函数来创建唯一对象：

我们拥有的构造函数很棒，但是如果我们不总是想创建相同的对象呢？

要解决这个问题，我们可以在构造函数中添加参数。我们这样做如下例所示：

var Car = function(wheels, seats, engines) {
  this.wheels = wheels;
  this.seats = seats;
  this.engines = engines;
};

现在我们可以在调用构造函数时传入参数。

var myCar = new Car(6, 3, 1);

此代码将创建一个使用我们传入的参数的对象，如下所示：

{
  wheels: 6,
  seats: 3,
  engines: 1
}

现在试一试吧！更改Car constructor以使用parameters为wheels, seats, and engines属性分配值。

然后使用三个数字参数调用您的新constructor并将其分配给myCar以查看其实际效果。

请填写以下代码：

  var Car = function() {
  //Change this constructor
  this.wheels = 4;
  this.seats = 1;
  this.engines = 1;
};

//Try it out here
var myCar;

说明：

调用new Car(3,1,2)应生成一个wheels的对象属性3，seats属性为1，engines属性为2.
调用new Car(4,4,2)应生成一个wheels的对象属性为4，seats属性为4，engines属性为2.
调用new Car(2,6,3)应生成一个wheels的对象属性为2，seats属性为6，engines属性为3.
myCar应具有wheels, seats, and engines的数字值属性。

我的尝试：

var Car = function() {
  //Change this constructor
  this.wheels = 4;
  this.seats = 1;
  this.engines = 1;
};

//Try it out here
var myCar = function(wheels, seats, engines) {
  this.wheels = wheels;
  this.seats = seats;
  this.engines = engines;
};
 var myCar = new Car(6, 3, 1);

Answer 1

你自己回答：

var Car = function(wheels, seats, engines) {
  //additional checks
  if(isNaN(wheels))
      wheels = 0;
  if(isNaN(seats))
      seats = 0;
  if(isNaN(engines))
      engines = 0;
  this.wheels = wheels;
  this.seats = seats;
  this.engines = engines;
};

//Try it out here
var myCar = new Car(3,1,2);
console.dir(myCar);

myCar = new Car(4,4,2);
console.dir(myCar);

myCar = new Car(2,6,3);
console.dir(myCar);

Answer 2

您添加的链接的编码质询答案将是：

var Car = function(wheels, seats, engines) {
 if(isNaN(wheels))
    wheels = 0;
 if(isNaN(seats))
    seats = 0;
 if(isNaN(engines))
    engines = 0;
  this.wheels = wheels;
  this.seats = seats;
  this.engines = engines;
};
//Try it out here
var myCar = new Car(2,6,3);
myCar = new Car(3,1,2);
myCar = new Car(4,4,2);

添加此代码后运行测试。 - 一切都会通过

通过将参数传递给构造函数来创建唯一对象

2 个答案: