CODEWITHSUNDEEP
javascript
Eric Larson
Eric Larson

Reputation: 519

Using Prototypes Over Classes In JavaScript

Is there a reason to use prototypes over classes? If I understand correctly, prototypes would be more efficient if I had defined functions in the constructor (but that is not the case here). Is the only thing different between these implementations syntax?

    class Quiz {
    constructor(questions) {
        this.score = 0;
        this.questionArray = questions;
        this.questionIndex = 0;
    }

    getCurrentQuestionObj() {
        return this.questionArray[this.questionIndex];
    }

    isGameOver() {
        return this.questionArray.length === this.questionIndex;
    }

    guess(answer) {
        if(this.getCurrentQuestionObj().isCorrectAnswer(answer)) {
            this.score++;
        }
        this.questionIndex++;
    }
}

-

function Quiz(questions) {
    this.score = 0;
    this.questions = questions;
    this.questionIndex = 0;
}

Quiz.prototype.getCurrentQuestionObj = function() {
    return this.questions[this.questionIndex];
}

Quiz.prototype.isGameOver = function() {
    return this.questions.length === this.questionIndex;
}

Quiz.prototype.guess = function(answer) {
    if(this.getCurrentQuestionObj().correctAnswer(answer)) {
        this.score++;
    }
    this.questionIndex++;
}

Upvotes: 0

Views: 36

Answers (1)

john_omalley
john_omalley

Reputation: 1398

ES6 classes are nothing more than sugar. Your two examples are equivalent.

Regarding functions declared in the constructor - you're right that those would be slightly less efficient. If you set 'this.foo = function() {}' in the constructor a new function is created every time you instantiate using the constructor.

Upvotes: 2

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