创建函数方法的演变

2017-08-19  本文已影响0人  馋中解禅

1.函数声明

function test1(a){
  a();
}
function test2(){
  console.log("执行啦!");
}
test1(test2);//输出:"执行啦!"

2.函数表达式

var test=function(){
  console.log("执行啦!");
}
test();//输出:"执行啦!"

3.工厂模式

function createPerson(name, sex, age) {
  var obj = new Object();
  obj.name = name;
  obj.sex = sex;
  obj.age = age;
  obj.sayName = function () {
    console.log("My name is Tom");
  };
  return obj;
}

var p1 = createPerson('Tom', '男', 20);
var p2 = createPerson('Jack', '男', 21);
console.log(p1.name);//输出:"Tom"
console.log(p2.name);//输出:"Jack"

4.构造函数模式

//首字母大写
function Person(name,sex,age){
  this.name=name;
  this.sex=sex;
  this.age=age;
  this.sayName=function(){
    console.log("My name is Tom");
  }
}
var p1=new Person('Tom','男',20);
var p2=new Person('Jack','男',21);
console.log(p1.constructor===Person);//输出:true
console.log(p1 instanceof Person);//输出:true
console.log(p1.sex===p2.sex);//输出:true
console.log(p1.sayName===p2.sayName);//输出:false

//函数优化,避免内部函数重复创建
function Person(name,sex,age){
  this.name=name;
  this.sex=sex;
  this.age=age;
  this.sayName=sayName;
}
function sayName(){
    console.log("My name is Tom");
  }
var p1=new Person('Tom','男',20);
var p2=new Person('Jack','男',21);
console.log(p1.sayName===p2.sayName);//输出:true
p1.sayName();//输出:"My name is Tom"

5.原型模式

function Person(){
}
var obj=Person.prototype;
obj.name='Tom';
obj.sex='20';
obj.sayName=function(){
  console.log("My name is Tom");
}
var p1=new Person();
var p2=new Person();
console.log(p1.name);//输出:"Tom"
console.log(p1.sayName===p2.sayName);//输出:true
console.log(p1.prototype);//输出:undefind
//原型对象.constructor=构造函数
//构造函数.prototype=原型对象
//实例对象=new 构造函数
//原型对象.isPrototypeOf(实例对象) true

6.组合构造函数模式和原型模式

function Person(name,sex,age){
  this.name=name;
  this.sex=sex;
  this.age=age;
  this.friends=["zhangsan","lisi"];
}
Person.prototype={
  constructor:Person,
  sayName:function(){
    console.log("My name is Tom");
  }
}

var p1=new Person('Tom','男',20);
var p2=new Person('Jack','男',21);
p1.friends.push("wangwu");
console.log(p1.friends);//输出:["zhangsan","lisi","wangwu"]
console.log(p2.friends);//输出:["zhangsan","lisi"]
console.log(p1.sayName===p2.sayName);//输出:true

7.class模式

class  Person{
  constructor(name,sex,age){
    this.name = name;
    this.sex = sex;
    this.age = age;
  }
  sayName(){
    console.log("My name is Tom");
  }
}
var p1=new Person('Tom','男',20);
var p2=new Person('Jack','男',21);
console.log(p1.name);//输出:"Tom"
console.log(p1.sayName===p2.sayName);//输出:true
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