js继承的这6种方式！（上）

//父级-构造函数
function Father() {
 this.fatherProp = true
}

//父级-原型属性
Father.prototype.getFatherValue = function() {
 return this.fatherProp
}

//子级-构造函数
function Son() {
 this.sonProp = false
}

//子级-原型属性：继承父级
//即__proto__指向父级的prototype
//若不理解请阅读《一张图彻底KO原型链(prototype,__proto__》
Son.prototype = new Father()

//子级-添加原型方法
Son.prototype.getSonValue = function() {
 return this.sonProp
}

//创建子级的实例对象
var son = new Son()
console.log(son.getFatherValue()) //true

//一个不存在的方法
console.log(son.getValue()) //ERROE：not a function

//子级-原型属性：继承父级
Son.prototype = new Father()

//不能像下面这样，这样会使得上面的代码无效
//因为这相当于重新创建了一个原型对象
Son.prototype = {
 getSonValue: function() {
  return this.sonProp
 }
}

 function Father() {
  this.arr = [1,2,3]
 }

 function Son() {
 }

 Son.prototype = new Father()

 var son1 = new Son()
 console.log(son1.arr) //1,2,3

 var son2 = new Son()
 son2.arr.push(4)

 console.log(son2.arr) //1,2,3,4
 console.log(son1.arr) //1,2,3,4

 function Father() {
  this.arr = [1,2,3]
 }

 function Son() {
  //call的第一个函数是this指向的对象,即构造函数的实例对象
  Father.call(this)

  /*上面代码等同于下面这段代码：
  (function() {
   this.arr = [1,2,3]
  }).call(this)
  */
 }

 var son1 = new Son()
 console.log(son1.arr) //1,2,3

 var son2 = new Son()
 son2.arr.push(4)

 console.log(son2.arr) //1,2,3,4
 console.log(son1.arr) //1,2,3

//解决传参问题：
function Father(name) {
 this.name = name
}

function Son(name) {
 Father.call(this, name)
}

var son1 = new Son("小名")
console.log(son1.name)  //小名

var son2 = new Son("一灯")
console.log(son2.name)  //一灯

function Father(name) {
 this.name = name
 this.arr = [1,2,3]
}

Father.prototype.getName = function() {
 console.log(this.name)
}

function Son(name, age) {
 Father.call(this, name)
 this.age = age
}

Son.prototype = new Father()
Son.prototype.constructor = Son
Son.prototype.getAge = function() {
 console.log(this.age)
}

var son1 = new Son("小名", 23)
son1.arr.push(4)
console.log(son1.arr) //1,2,3,4
son1.getName()    //小名
son1.getAge()     //23

var son2 = new Son("一灯", 24)
console.log(son2.arr) //1,2,3
son1.getName()    //一灯
son1.getAge()     //24