JavaScript之new与不new的区别

 

new 和不 new的区别：

•  如果 new 了函数内的 this 会指向当前这个 person 并且就算函数内部不 return 也会返回一个对象。
•  如果不 new 的话函数内的 this 指向的是 window。

function person(firstname,lastname,age,eyecolor)
{
    this.firstname=firstname;
    this.lastname=lastname;
    this.age=age;
    this.eyecolor=eyecolor;
    return [this.firstname,this.lastname,this.age,this.eyecolor,this] 
}

var myFather=new person("John","Doe",50,"blue");
var myMother=person("Sally","Rally",48,"green");
console.log(myFather) 
console.log(typeof myFather) 
console.log(myMother) 
console.log(typeof myMother) 

 

 

 

function person(firstname,lastname,age,eyecolor)
{
    this.firstname=firstname;
    this.lastname=lastname;
    this.age=age;
    this.eyecolor=eyecolor;
//     return [this.firstname,this.lastname,this.age,this.eyecolor,this] 
}

var myFather=new person("John","Doe",50,"blue");
var myMother=person("Sally","Rally",48,"green");
console.log(myFather) 
console.log(typeof myFather) 
console.log(myMother) 
console.log(typeof myMother)