JS 如何实现继承

B(子类)-->A(父类) ,继承可以使子类具有父类的各种属性和方法

//汽车(类)，属性：颜色、轮胎、品牌...

//轿车：后备箱

//货车：大货箱

1.原型链的继承

function Person() {

this name = "person",

this arr = [1,2,3,4]

}

console.log(new Person());

function Child() {

this.type = "child"

}

Child prototype = new Person()

var c1 = new Child()

var c2 = new Child()

c1.arr.push(5)

console.log(c1);

console.log(c2);

//子类的实例对象是同一个

//2.构造函数继承

function Person() {

this.name = "Person";

this.arr = [1,2,3,4]

}

Person.prototype.age=18

function Child(){

Person.call(this)

this.type = "child"

}

//console.log(new Child());

var c1 = new Child()

var c2 = new Child()

c1.arr.push(5)

console.log(c1);

console.log(c2);

//构造函数不能继承原型属性的方法和属性

//3.组合继承

function Person() {

this.name = "Person";

this.arr = [1,2,3,4]

}

Person.prototype.age=18

function Child(){

Person.call(this)

this.type = "child"

}

Child.prototype = new Person();

Child.prototype.constructor=Child

var c1 = new Child()

var c2 = new Child()

console.log(c1.constructor);

c1.arr.push(5)

console.log(c1);

console.log(c2);