Class usage and inheritance in ES6

（ One ）class The goal is to make defining classes easier

Let's review the implementation of functions Peopel Methods ：

function Peopel(name) {
    
    this.name = name;
}
Peopel.prototype.hello = function () {
    
    console.log('Hello, ' + this.name + '!');
}

If you use a new class Keywords to write Peopel, It can be written like this ：

//  Capitalize the beginning of the class 
class Peopel {
    
	//  Constructor construction properties 
    constructor(name) {
    
        this.name = name;
    }
    //  Method 
    hello() {
    
        console.log('Hello, ' + this.name + '!');
    }
}

A comparison shows that ,class The definition of contains constructors constructor And functions defined on prototype objects hello()（ Note that there is no function keyword ）, This avoids Student.prototype.hello = function () {...} This decentralized code .

//  Create an instance of a person 
var xiaoming = new Peopel(' Xiao Ming ');
console.log(xiaoming.name); //  Xiao Ming 
xiaoming.hello(); // hello, Xiao Ming ！

（ Two ） Class inheritance

Inherited parent class , adopt extends To achieve , Method can call directly , Property needs to be called super To carry out

//  Parent class 
class Peopel {
    
    constructor(name) {
    
        this.name = name;
    }
    eat() {
    
        console.log(`${
      this.name} eat something`);
    }
}
//  Subclass inheritance Peopel
//  Be careful Student The definition of is also class Keyword implementation of , and extends It means that the prototype chain object comes from Peopel
class Student extends Peopel {
    
    constructor(name, number) {
    
        super(name); // call super(), Instead of the parent constructor , Initializes properties common to the parent class 
        this.number = number;
    }
    information() {
    
        console.log(` full name ：${
      this.name},  Student number ：${
      this.number}`)
    }
}
//  Subclass inheritance Peopel
class Teach extends Peopel {
    
    constructor(name, major) {
    
        super(name);
        this.major = major;
    }
    teach() {
    
        console.log(` full name ：${
      this.name},  Major ：${
      this.major}`)
    }
}

example

//  Create an instance of a student 
const newStudent = new Student('wendy', 101);
console.log(newStudent.name); // wendy
console.log(newStudent.number); // 101
newStudent.information(); //  full name ：wendy, Student number ：101

//  Create an instance of a teacher 
const newTeacher = new Teach(' Mr. Wen ', ' Chinese language and literature ');
console.log(newTeacher.name); //  Mr. Wen 
console.log(newTeacher.major); //  Chinese language and literature 
newTeacher.teach(); //  full name ： Mr. Wen , Major ： Chinese language and literature