New with JavaScript. Can someone help me understand why calling print() returns undefined?
class Quizer {
constructor(quizObj) {
this.quiz = quizObj;
}
print() {
console.log(quiz.title);
}
};
var quizObjects = {
title: "Quiz1"
};
Constructing:
var quiz = new Quizer(quizObjects);
quiz.print(); //undefined
The problems with your code are,
class Quizer {
constructor(quizObj) {
this.quiz = quizObj;
}
print() {
console.log(quiz.title);
//You are not using the `this` context here to access the quiz
//you have a variable quiz outside the class declaration that points the instance of this class.
//That will get hoisted and will be accessed here.
}
};
var quizObjects = { title: "Quiz1" };
var quiz = new Quizer(quizObjects);
quiz.printAllQuestions(); //undefined
//--------^^^^ printAllQuestions is not a member function of Quizer
Solution:
class Quizer {
constructor(quizObj) {
this.quiz = quizObj;
}
print() {
console.log(this.quiz.title);
}
};
var quizObjects = { title: "Quiz1" };
var quiz = new Quizer(quizObjects);
quiz.print(); //Quiz1
If you're not much familiar with class syntax yet, the below should work as well.
Quizer = function (quizObj) {
this.quiz = quizObj;
};
Quizer.prototype = {
print: function () {
console.log(this.quiz.title);
}
}
var quizObjects = { title: "Quiz1" };
var quiz = new Quizer(quizObjects);
quiz.print();
