学到的新的javascript继承方法

最新推荐文章于 2024-09-07 14:47:56 发布

zhangjinyi

最新推荐文章于 2024-09-07 14:47:56 发布

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分类专栏： Javascript 文章标签： javascript function constructor class object string

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本文详细介绍了JavaScript中类的定义、实例化、方法、属性的使用，并通过实例展示了原型链、构造函数、原型继承的实现过程。

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// class Pet
function Pet(name) {
    this.getName = function() { return name; };
    this.setName = function(newName) { name = newName; };
}

Pet.prototype.toString = function() {
    return “This pet’s name is: “ + this.getName();
};
// end of class Pet

var parrotty = new Pet(“Parrotty the Parrot”);
alert(parrotty);

// class Dog : Pet 
// public Dog(string name, string breed)
function Dog(name, breed) {
    // think Dog : base(name) 
    Pet.call(this, name);
    this.getBreed = function() { return breed; };
    // Breed doesn’t change, obviously! It’s read only.
    // this.setBreed = function(newBreed) { name = newName; };
}

// this makes Dog.prototype inherits
// from Pet.prototype
Dog.prototype = new Pet();

// remember that Pet.prototype.constructor
// points to Pet. We want our Dog instances’
// constructor to point to Dog.
Dog.prototype.constructor = Dog;

// Now we override Pet.prototype.toString
Dog.prototype.toString = function() {
    return “This dog’s name is: “ + this.getName() + 
        “, and its breed is: “ + this.getBreed();
};
// end of class Dog

var dog = new Dog(“Buddy”, “Great Dane”);
// test the new toString()
alert(dog);

// Testing instanceof (similar to the is operator)
// (dog is Dog)? yes
alert(dog instanceof Dog);
// (dog is Pet)? yes
alert(dog instanceof Pet);
// (dog is Object)? yes
alert(dog instanceof Object);