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A brief analysis of JS prototype inheritance and class inheritance_Basic knowledge
A brief analysis of JS prototype inheritance and class inheritance_Basic knowledge
Let’s look at the inheritance of JS classes first
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>JS类的继承</title>
</head>
<body>
/* -- 类式继承 -- */
<script type="text/javascript">
//先声明一个超类
var Animal = function(name) {
this.name = name;
}
//给这个超类的原型对象上添加方法
Animal.prototype.Eat = function() {
console.log(this.name + " Eat");
};
//实例化这个超
var a = new Animal("Animal");
//再创建构造函数对象类
var Cat = function(name, sex) {
//这个类中要调用超类Animal的构造函数，并将参数name传给它
Animal.call(this, name);
this.sex = sex;
}
//这个子类的原型对象等于超类的实例
Cat.prototype = new Animal();
//因为子类的原型对象等于超类的实例，所以prototype.constructor这个方法也等于超类构造函数
console.log(Cat.prototype.constructor);
//这个是Animal超类的引用，所以要从新赋值为自己本身
Cat.prototype.constructor = Cat;
console.log(Cat.prototype.constructor);
//子类本身添加了getSex 方法
Cat.prototype.getSex = function() {
return this.sex;
}
//实例化这个子类
var _m = new Cat('cat', 'male');
//自身的方法
console.log(_m.getSex()); //male
//继承超类的方法
console.log(_m.Eat()); //cat
</script>
</body>
</html>Let’s look at JS prototypal inheritance
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>JS原型继承</title>
</head>
<body>
<!--原型继承-->
<script type="text/javascript">
//clone()函数用来创建新的类Person对象
var clone = function(obj) {
var _f = function() {};
//这句是原型式继承最核心的地方，函数的原型对象为对象字面量
_f.prototype = obj;
return new _f;
}
//先声明一个对象字面量
var Animal = {
somthing: 'apple',
eat: function() {
console.log("eat " + this.somthing);
}
}
//不需要定义一个Person的子类，只要执行一次克隆即可
var Cat = clone(Animal);
//可以直接获得Person提供的默认值，也可以添加或者修改属性和方法
console.log(Cat.eat());
Cat.somthing = 'orange';
console.log(Cat.eat());
//声明子类,执行一次克隆即可
var Someone = clone(Cat);
</script>
</body>
</html>We can try it out. JS class inheritance children.constructor==father returns true, while prototypal inheritance children.constructor==father returns false;
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