javascript - javascript 方法 "call"在此代码中如何工作

Question

大家好，我正在准备 Microsoft 认证考试 40-780 和书中的内容

Training Guide:Programming in HTML5 with Javascript and CSS3

他们展示了如何在 Javascript 中实现继承的示例。我需要对这行代码进行令人上瘾的解释:

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

此方法“调用”如何在代码上下文中实际工作。这是我上面提到的书中的代码示例。

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) {
    function Car(year, make, model) {
        parent.call(this, year, make, model); // <-- how this works?
        this.wheelQuantity = 4;
    }
    return Car;
})(Vehicle);

Answer 1

Car 类扩展了 Vehicle 类，Vehicle 中的所有“this.”都成为 Car 实例。所以如果你构造一个新的 Car 对象，结果会变成这样，

var c = new Car(2020,"EU","GSX");
Car {year: 2020, make: "EU", model: "GSX", wheelQuantity: 4}

有调用方法说明here