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JavaScript Object-Oriented JavaScript Working with Classes in JavaScript Adding methods to classes

Posted by Hanwen Zhang
Hanwen Zhang
20,084 Points

I don't quite understand what does 'String(this.gpa)' works here?

Also, why we don't need to add constructor(gpa, this.gpa)?

adding_methods.js 
class Student {
    constructor(gpa){
        this.gpa = gpa;
    }
  stringGPA() { 
    return String(this.gpa);
}
}

const student = new Student(3.9);

1 Answer

Peter Vann
Peter Vann
36,425 Points

Hi Hanwen!

this.gpa = gpa;

Just makes the value passed to the class constructor a class/instance attribute/property and as such whenever you need to access it within the class instance you need to reference it with this.gpa.

"this" being that particular class instance.

The String() function just casts/converts the numeric value to a string.

More info:

https://www.w3schools.com/js/js_classes.asp

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this

I hope that helps.

Stay safe and happy coding!

Hanwen Zhang
Hanwen Zhang
20,084 Points

Got it! Thank you, Peter