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Understanding JavaScript’s super()

The super() keyword is an important part of the JavaScript language and is used in object-oriented programming. It is used to refer to a parent class or object, and can be used to call methods or access properties of the parent.

What is super()?

The super() keyword is used to refer to a parent class or object, and can be used to call methods or access properties of the parent. It is used in object-oriented programming to refer to the parent of the current object.

It is important to note that super() must be used within a class definition. It cannot be used outside of the class.

How to Use super()

In order to use the super() keyword, you must first create a class that has a parent class. For example, we could create a Person class and a Student class that inherits from Person:

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class Person {
    constructor(name){
        this.name = name;
    }
    sayName(){
        console.log(this.name);
    }
}

class Student extends Person {
    constructor(name, grade){
        super(name);
        this.grade = grade;
    }
    sayGrade(){
        console.log(this.grade);
    }
}

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In this example, the Student class is a child class of the Person class. The super() keyword is used in the Student class constructor to call the parent Person class constructor and pass in the name argument. This allows us to access the name property in the Student class.

We can also use the super() keyword to access methods in the parent class. For example, we could add a sayName() method to the Student class that calls the sayName() method of the parent Person class:

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class Student extends Person {
    constructor(name, grade){
        super(name);
        this.grade = grade;
    }
    sayName(){
        super.sayName();
    }
    sayGrade(){
        console.log(this.grade);
    }
}

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In this example, the sayName() method of the Student class calls the sayName() method of the Person class using the super() keyword.

Conclusion

The super() keyword is an important part of the JavaScript language and is used in object-oriented programming. It is used to refer to a parent class or object, and can be used to call methods or access properties of the parent. It is important to note that super() must be used within a class definition, and cannot be used outside of the class.