对象继承的四种方式

阳光穿透心脏的1/2处 2022-03-09 12:36 311阅读 0赞

1.传统的继承方式-原型链形式：缺点：过多的继承了没有用的属性 比如Father工厂里面创建的name

Father.prototype.lastName = "teng";
    		function Father(){
    			this.name = "anchao"
    		}
    		var father = new Father();
    		Son.prototype =father;
    		function Son(){
    
    		}
    		var son = new Son();

2.借用构造函数来继承，使用call和apply改变this指向，借用别人的工厂创建了自己的对象。缺点：不能继承别人工厂的原型 比如访问student.address = undefined;

Person.prototype.address = "地球";
    		function Person(name,sex,age){
    			this.name = name;
    			this.sex = sex;
    			this.age = age;
    			this.sing = function(){
    				console.log("I am"+this.name);
    			}
    		}
    		function Student(name,sex,age,className){
    			Person.call(this,name,sex,age);
    			this.className = className;
    		}
    
    		var student = new Student("tenganchao","male",26,"三年五班");

3.共享原型来继承。缺点：不能更改儿子的原型，否则父亲的原型也跟着变化

Father2.prototype.lastName = "teng";
    		function Father2(){
    			this.name = "anchao"
    		}
    		function Son2(){
    
    		}
    		function inherit(Target,Origin){
    			Target.prototype = Origin.prototype
    		}
    		inherit(Son2,Father2);
    
    		var son2 = new Son2();

4.圣杯模式。在共享原型的基础上，通过一个function F()\{\} 来改掉共享原型上的缺点，这样即能达到继承效果，又可以在自己原型链上进行更改

Father3.prototype.lastName = "teng";
    
    		function Father3(){
    
    		}
    		function Son3(){
    
    		}
    		function inherit3(Target,Origin){
    			function F(){};
    			F.prototype = Origin.prototype;//将原构(父)造函数与F构造函数共享一个原型
    			Target.prototype = new F();//将目标(子)构造函数的原型指向了通过new F()创建的对象
    			Target.prototype.constuctor = Target;//将constructor复原
    			Target.prototype.uber = Origin.prototype;//查找继承的超类
    		}
    		inherit3(Son3,Father3);
    
    		var son3 = new Son3();