JavaScript函数与创建对象

通过new的方式创建对象，自己会返回一个对象

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 myFather2 = 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)
console.log("----------")

2. 函数带有返回值过后， new与执行函数都会返回一个数组

 

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 myFather2 = 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)
console.log("----------")
​
 

3. 在创建对象后，对象自己可以通过“实例名.xxx”添加，但是这个函数的其他对象无法得到新的属性。

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 myFather2 = 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)
console.log("----------")

myFather.dd = ()=>{
    console.log("ddddddd")
}

myFather.name = "new name"

person.prototype.ff = function() {
    return console.log("fffff");
}

console.log(myFather.name)
myFather.dd()
//myFather2.dd()//报错
myFather.ff()
//myMother.ff()//报错