实现继承的几种方法总结
1.构造函数绑定:使用 call 或 apply 方法,将父对象的构造函数绑定在子对象上
function Cat(name,color){
Animal.apply(this, arguments);
this.name = name;
this.color = color;
}
2.实例继承:将子对象的 prototype 指向父对象的一个实例
Cat.prototype = new Animal();
Cat.prototype.constructor = Cat;
3.拷贝继承:如果把父对象的所有属性和方法,拷贝进子对象
function extend(Child, Parent) {
var p = Parent.prototype;
var c = Child.prototype;
for (var i in p) {
c[i] = p[i];
}
c.uber = p;
}
4.原型继承:将子对象的 prototype 指向父对象的 prototype
function extend(Child, Parent) {
var F = function(){};
F.prototype = Parent.prototype;
Child.prototype = new F();
Child.prototype.constructor = Child;
Child.uber = Parent.prototype;
}
5.ES6 语法糖 extends:class ColorPoint extends Point {}
class ColorPoint extends Point {
constructor(x, y, color) {
super(x, y); // 调用父类的constructor(x, y)
this.color = color;
}
toString() {
return this.color + ' ' + super.toString(); // 调用父类的toString()
}
}