What is a class in javascript

In JavaScript, a class is a user-defined type, also called a class type, which is a collection of groups with the same attributes and behaviors; starting from es6, you can define a class by creating the class keyword Template, for example "class class name {}".

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

What is a class

In object-oriented programming, a class is a template of an object and defines the same group of objects. (also called "instances") have properties and methods that are common to all instances. A class is a user-defined reference data type, also called a class type.

We can understand that a class is a collection of groups with the same attributes and behaviors.

Classes in JS

Before ES5, to express a class in JS, a method called The syntax style of prototype-based

	function 士兵(id,hp){
	    this.id = id
	    this.hp = hp
	}
	士兵.prototype = {
	    constructor:士兵()
	    walk:function(){ } ,
	    Shooting:function(){ } ,
	}

In es6, the concept of class was introduced for the first time, and the template of a class was defined by creating the class keyword.

1. Create a Class in js

class Number{
}

2. Implement the constructor, instance properties and instance methods of Class

//构造方法
class Number{
//实例属性
constructor(id,age){
//this指向当前事件
this.id=id;
this.age=age;
}
//实例方法
num(){
console.log("hh");
}
}
//实例化对象
var n1=new Number("1","2");
n1.num(1);
console.log(n1.id);
console.log(n1.age);
var n2=new Number("3","4");
n2.num(2);
console.log(n2.id);
console.log(n2.age);

Effect display:

hh
1
2
hh
3
4

3. Static properties and static methods of Class

//构造方法
class Number{
//静态属性调用一个方法
static ppp=1;
//实例属性
constructor(id,age){
//this指向当前事件
this.id=id;
this.age=age;
console.log(Number.ppp)
}
//实例方法
num(){
console.log("hh");
}}
//实例化对象
var n1=new Number("1","2");
n1.num(1);
console.log(n1.id);
console.log(n1.age);
var n2=new Number("3","4");
n2.num(2);
console.log(n2.id);
console.log(n2.age);

Effect display:

1
hh
1
2
1
hh
3
4

4.Class inheritance

//父类
class Father{
//构造方法不能被继承
constructor(){
console.log("我是父亲");
this.name="father"
}
}
//子类
class Son extend Father{
//执行子类构造方法之前必须先执行父类构造方法
constructor(){
super();//执行父类构造方法
console.log("我是儿子")
}
}
var son=new Son;
console.log(son.name)

Effect display:

我是父亲
我是儿子
father

[Recommended learning: javascript advanced tutorial]

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