Multiple ways to add properties and methods to JS objects

Method 1: When defining an object, add properties and methods directly

function Person(name,age,sex){
    this.name = name;
    this.age = age;
    this.sex = sex;
    this.code = function(){
        console.log(this.name + " is coding");
    }
}

var xiaoming = new Person("xiaoming",10,"man");
console.log(xiaoming);// {name: "xiaoming", age: 10, sex: "man", code: ƒ}
xiaoming.code();// xiaoming is coding 

operation result:

Person {

  name: 'xiaoming',

  age: 10,

  sex: 'man',

  code: [Function (anonymous)]

}

Xiaoming is coding

 
Method 2: Add properties and methods through "object.property name"

function Fruit(){}

var tomato = new Fruit();
tomato.name = "xihongshi";
tomato.color = "red";
tomato.use = function(){
    console.log(this.name + " can be to eat");
}
console.log(tomato);
tomato.use();

operation result:

Fruit { name: 'xihongshi', color: 'red', use: [Function (anonymous)] }

Xihongshi can be to eat

Method 3: Add properties and methods through "object [ 'property name' ] "

function Fruit(){}

var tomato = new Fruit();
tomato['name'] = "xihongshi";
tomato['color'] = "red";
tomato['use'] = function(){
    console.log(this.name + " can be to eat");
}
console.log(tomato);
tomato.use();

operation result:

Fruit { name: 'xihongshi', color: 'red', use: [Function (anonymous)] }

Xihongshi can be to eat

Method 4: Add properties and methods through prototype (prototype)

function Animal(){};

Animal.prototype.foots = 4;
Animal.prototype.weight = 200;
Animal.prototype.hobby = "sing";
Animal.prototype.have = function(){
    console.log("the animal have " + this.foots + " foot");
}

var pig = new Animal();
console.log(pig);
pig.have();// the animal have 4 foot

operation result:

Animal {}

the animal have 4 foot

Way 5: Use Object.assign to add properties and methods

function Person(name,age,sex){
    this.name = name;
    this.age = age;
    this.sex = sex;
    this.code = function(){
        console.log(this.name + " is coding");
    }
}

var xiaoming = new Person("xiaoming",10,"man");
console.log(xiaoming);// {name: "xiaoming", age: 10, sex: "man", code: ƒ}
xiaoming.code();// xiaoming is coding   

var xiaoming2 = Object.assign({}, xiaoming, {test1:'demo1', test2:'demo2'}); // 第一个参数是 目标对象，后面的全是源对象，执行完之后返回目标对象
console.log(xiaoming2);// {name: "xiaoming", age: 10, sex: "man", code: ƒ, test1: 'demo1', test2: 'demo2'}
xiaoming2.code();// xiaoming is coding   

operation result:

Person {

  name: 'xiaoming',

  age: 10,

  sex: 'man',

  code: [Function (anonymous)]

}

xiaoming is coding

{

  name: 'xiaoming',

  age: 10,

  sex: 'man',

  code: [Function (anonymous)],

  test1: 'demo1',

  test2: 'demo2'

}

xiaoming is coding

Method 6: Use the spread operator ... to add properties and methods

ES6 has a new syntax that can combine two objects into one object. Merge multiple properties into 1 object.

function Person(name,age,sex){
    this.name = name;
    this.age = age;
    this.sex = sex;
    this.code = function(){
        console.log(this.name + " is coding");
    }
}

var xiaoming = new Person("xiaoming",10,"man");
console.log(xiaoming);// {name: "xiaoming", age: 10, sex: "man", code: ƒ}
xiaoming.code();// xiaoming is coding   

var xiaoming2 = {...xiaoming, test1:'demo1', test2:'demo2'};
console.log(xiaoming2);// {name: "xiaoming", age: 10, sex: "man", code: ƒ, test1: 'demo1', test2: 'demo2'}
xiaoming2.code();// xiaoming is coding   

operation result:

Person {

  name: 'xiaoming',

  age: 10,

  sex: 'man',

  code: [Function (anonymous)]

}

xiaoming is coding

{

  name: 'xiaoming',

  age: 10,

  sex: 'man',

  code: [Function (anonymous)],

  test1: 'demo1',

  test2: 'demo2'

}

xiaoming is coding