ES6 Object-Oriented Programming

// OOP encapsulation
class Student{ // Define a class (follows the convention of capitalizing the first letter)
    constructor(props){  // Constructor (properties are defined inside the constructor)
        this.name = props.name || 'Anonymous'; // Default 'Anonymous'
      this.grade = props.grade || 1;
    }
    hello(){ // Define methods on the constructor's prototype
        console.log(`Hello, ${this.name}, you are in grade ${this.grade}`);
    }
}



// Usage
function createStudent(props) { // A wrapper for new constructor, with two benefits: 1) no need to use new, 2) flexible parameters
    return new Student(props || {}) // Create an instance via new constructor and pass in parameters/properties
}

let niming = createStudent();
niming.hello();

let xiaoming = createStudent({
  name:'Xiaoming',
  grade:2
});
xiaoming.hello();



// Inheritance
class PrimaryStudent extends Student { // class ChildClass extends ParentClass
    constructor(props) {
        super(props); // Use super to call the parent's constructor to inherit properties
        this.age = props.age || 8; // Add a new child class property
    }

    getAge() { // Add a method to the child class
        console.log(`${this.name}, you are ${this.age} years old`);
    }
}


// Using the inherited class
function createPrimaryStudent(props) { // A wrapper for new constructor, with two benefits: 1) no need to use new, 2) flexible parameters
    return new PrimaryStudent(props || {}) // Create an instance via new constructor and pass in parameters/properties
}

let xiaohong = createPrimaryStudent({
  name:'Xiaohong',
  grade:3,
  age:10
});
xiaohong.hello();
xiaohong.getAge();