WEB开发编程网Javascript有一个有趣的继承模型，它与大多数OOP语言完全不同。虽然它是面向对象的，但对象没有从其获取方法的类。相反，它已具雏形， 这被称为基于原型的继承（与对比基于类的继承） ，以了解这两者之间的区别，因为它们是不等价的，并导致许多混乱的路线是很重要的。 尽管JavaScript有自推出关键字支持OOP，这是其基于原型的继承模型只是语法糖-一切都没有从根本上改变。
class
用function关键字 定义一个类
让我们来看看一个“类”，使用已定义function关键字：
function Animal(name, energy) {
// _secret is a private property, which cannot be accessed with a dot-notation
const _secret = 100;
// name and energy are public properties, can be accessed with a dot-notation
this.name = name;
this.energy = energy;
// this function is public, and returns the value of the private _secret property (but prevents it from being modified)
this.getSecret = () => _secret;
}
// all properties under prototype are shared methods across all instances of a function.
Animal.prototype.sleep = function(energyReplenished) {
console.log(`${this.name} is sleeping.`);
this.energy += energyReplenished;
};
Animal.prototype.play = function(energyLost) {
console.log(`${this.name} is playing.`);
this.energy -= energyLost;
};
注： _secret是私有财产不是因为_它的变量名称的前缀，而是因为我们没有特别把它定义为一个属性this。
基于原型的继承
现在，让我们来看看继承：
function Dog(name, energy, breed) {
// every instance of Dog will now have a name and energy property.
Animal.call(this, name, energy); // look at the Animal function above - notice how it takes in `name` and `energy` as the two parameters
// in addition to the properties created by the Animal function, Dog also has its own properties now as well
this.breed = breed;
}
// Dog has the same prototypes that are definded in Animal,
Dog.prototype = Object.create(Animal.prototype);
// but also some of its own as well:
Dog.prototype.bark = function () {
console.log('Woof Woof!');
this.energy -= 0.1;
}
// Let Dog's constructor point to itself, not Animal
Dog.prototype.constructor = Dog;
感谢您的阅读，希望您喜欢！
坍方
