罕用的继承形式
1：原型链继承
function Child(){ this.age="10";}function Father(){ this.name="father"; this.friends=['a','b'];}Father.prototype.sayName=function(){ console.log(this.name);}Child.prototype=new Father();Child.prototype.constructor=Child;var c1=new Child();var c2=new Child();c2.friends.push('c');/**顾名思义通过原型prototype对象进行继承，原型链向上查找公共属性办法.Child.prototype指向了Father实例毛病:1:无奈向父类传递参数用于结构。2:父类的name,firends公有属性，都成子类原型私有属性。c2.friends.push('c');执行后c1.firends也被批改 c2.friends==c1.friends==['a','b','c']*/
2：构造函数继承
function Child(data){ this.age="10"; Father.call(this,data)}function Father(data){ this.name=data.name; this.friends=data.friends; this.sayName=function(){ console.log(this.name) } console.log("被执行了") }Father.prototype.showFriends=function(){ console.log(this.showFriends);}var c1=new Child({ name:'c1', friends:['a','b']})var c2=new Child({ name:'c2', friends:['c','d']})c1.friends.push('x')c2.friends.push('y')/**通过call|apply进行继承(属性拷贝),与prototype没有关系能够向子类传递结构参数，子类继承的父类属性独立.实现所有属性办法独享.毛病：1：雷同公共办法sayName没抽离,所有子类都有本人独立的sayName,(c1.sayName===c2.sayName)false*/
3：原型继承+call继承（组合继承）
function Child(data){ Father.call(this,data)}function Father(data){ this.name=data?data.name:"father"; this.friends=data?data.friends:[]; console.log("Father构造函数执行了")}Father.prototype.showFriends=function(){ console.log(this.friends)}Child.prototype=new Father();Child.prototype.constructor=Child;var c1=new Child({ name:'c1', friends:['a','b']})var c2=new Child({ name:'c2', friends:['c','d']})c1.friends.push('x')c2.friends.push('y')c1.showFriends()c2.showFriends()/**公有属性构造函数继承，公共属性办法原型链实现。毛病:1:调用了两次父类构造函数，生成了两份实例Father.call，Child.prototype=new Father();*/
4：寄生式继承
function createObj(o){ function F(){ } F.prototype=o; return new F();}function Child(data){ Father.call(this,data)}function Father(data){ this.name=data?data.name:"father"; this.friends=data?data.friends:[]; console.log("Father构造函数执行了")}Father.prototype.showFriends=function(){ console.log(this.friends)}Father.prototype.likes=['吃','睡'];Child.prototype=createObj(Father.prototype);Child.prototype.constructor=Child;Child.prototype.childLikes=function(){ console.log('aaa')}var c1=new Child({ name:"c1", friends:['a','b']})var c2=new Child({ name:"c2", friends:['c','d']})var f1=new Father({ name:"f1", friends:['e','f']})c1.friends.push('x')c2.friends.push('y')console.log(c1,c2);/**应用两头空对象F来连接子类与父类，子类原型指向F实例F.prototype==Father.prototype,F没有公有属性因而new开销比拟小。*/
5：Class继承
class Father{ constructor(data){ this.name=data?data.name:"father"; this.friends=data?data.friends:[]; } showFriends(){ console.log(this.friends) }}class Child extends Father{ constructor(data){ super(data); }}var c1=new Child({ name:'c1', friends:['a','b']})var c2=new Child({ name:'c2', friends:['c','d']})c1.friends.push('x')c2.friends.push('y')console.log(c1,c2)/**和寄生式继承成果一样，简洁语义更好。子类构造函数必须先调用一次super*/