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JavaScript Object-Oriented JavaScript Getters and Setters Creating Setter Methods

Posted by Nas Jones
Nas Jones
7,849 Points

Completely confused

I watched the setter video before this and i was lost. set owner(owner) { this._owner = owner; console.log(setter called: ${owner}); }

If you look at this code i see four different places where "owner" was used before it was logged in the console, why were they used in each instance?. I also don't understand why the "_" was necessary. Also, in this challenge i'm confused as well, all i got out of it was an if statement i don't know what to do further. Also, if this can be explained simply that would help me better instead of using complex words and code

creating_setters.js 
class Student {
    constructor(gpa, credits){
        this.gpa = gpa;
        this.credits = credits;
    }

    stringGPA() {
        return this.gpa.toString();
    }

    get level() {
        if (this.credits > 90 ) {
            return 'Senior';
        } else if (this.credits > 60) {
            return 'Junior';
        } else if (this.credits > 30) {
            return 'Sophomore';
        } else {
            return 'Freshman';
        }
    }

  set major(major) {
  this._major = major;
  if (level == 'Senior' || level == 'Junior') {

  }



  }
















}

var student = new Student(3.9, 60);

1 Answer

Peter Vann
Peter Vann
36,425 Points

Hi Nas!

Sorry for the late response. Just saw this.

As to your first point:

This:

set owner(owner) {
    this._owner = owner;
    console.log(`setter called: ${owner}`);
}

Could just as easily be coded:

set owner(tmpParam) {
    this._owner = tmpParam;
    console.log(`setter called: ${tmpParam}`);
}

or even:

set owner(x) {
    this._owner = x;
    console.log(`setter called: ${x}`);
}

The parameter name is arbitrary, but "owner" makes sense in this context (albeit potentially confusing).

The preceding "_" denotes a "private" object property or method.

More info:

https://www.thoughtco.com/and-in-javascript-2037515

Obviously, this would pass task 1:

class Student {
    constructor(gpa, credits){
        this.gpa = gpa;
        this.credits = credits;
    }

    stringGPA() {
        return this.gpa.toString();
    }

    get level() {
        if (this.credits > 90 ) {
            return 'Senior';
        } else if (this.credits > 60) {
            return 'Junior';
        } else if (this.credits > 30) {
            return 'Sophomore';
        } else {
            return 'Freshman';
        }
    }

    set major(major) { // Task 1, which you already got

    }
}

var student = new Student(3.9, 60);

For this: Inside the major() setter method, set the student's major to a backing property "_major".

You would do this:

class Student {
    constructor(gpa, credits){
        this.gpa = gpa;
        this.credits = credits;
    }

    stringGPA() {
        return this.gpa.toString();
    }

    get level() {
        if (this.credits > 90 ) {
            return 'Senior';
        } else if (this.credits > 60) {
            return 'Junior';
        } else if (this.credits > 30) {
            return 'Sophomore';
        } else {
            return 'Freshman';
        }
    }

    set major(major) { 
        this._major = major; // First part of Task 2, which you already got
    }
}

var student = new Student(3.9, 60);

For this: If the student's level is Junior or Senior, the value of the backing property should be equal to the parameter passed to the setter method. If the student is only a Freshman or Sophomore, set the "_major" backing property equal to 'None'. Let me see if I can rephrase it more simply.

If the getter "level" (this.level) returns (is equal to) Freshman or Sophomore, change this._major to "None" otherwise leave it as the major parameter (don't change it).

I can show you that code if you can't solve it from the description now.

Please let me know.

I hope that helps.

Stay safe and happy coding!

Nas Jones
Nas Jones
7,849 Points

Hello thanking you for responding and trying to help i truly appreciate it. I passed the challenge thanks to your help i understood what you were saying for the most part. But i still kind of don't get it, i remember how the instructor in previous videos said how this can be confusing and i am confused. What is the goal of getters and setters in this case? what are we trying to achieve?. set owner(x) { this._owner = x; console.log(setter called: ${x}); } What happens if i pass something in the "x" parameter?, what can i pass in it?. Breaking it down to simple terms helps me.

Thank you for the help.