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JavaScript Object-Oriented JavaScript (2015) Practice Project Project Overview

Robert Tyree
Robert Tyree
13,335 Points
Posted by Robert Tyree
Robert Tyree
13,335 Points

Array returning "undefined" after push method

Hi there. I'm trying to understand why the push-method approach used in the Treetunes model doesn't seem to be functioning in the JavaScript below. Any idea why the final alert there would return undefined rather than with the question object?

Thanks a bunch for any tips!

//quiz.js

function Quiz() {
  this.questions = [];
  this.currentQuestionIndex = 0;
}

Quiz.prototype.add = function(question) {
  this.questions.push(question);
};

//question.js

function Question(question, choice0, choice1, answer) {
  this.question = question;
  this.choice0 = choice0;
  this.choice1 = choice1;
  this.answer = answer;
}

//app.js

var quiz = new Quiz();

var questionA = new Question("Where are you?", "Portland", "France", "France");
var questionB = new Question("Who are you?", "Joe", "Robert", "Robert");

quiz.add(questionA);
quiz.add(questionB);


alert(quiz[0].choice0);
//Not sure why this won't load! Why is the array position returning undefined?

The scripts are loaded in this order in the HTML file.

<script src="quiz.js"></script>
<script src="question.js"></script>
<script src="quiz_ui.js"></script>
<script src="app.js"></script>

1 Answer

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

:point_right: Your Quiz object is not an array, and has no property named "choice0".

Were you intending to access the first stored Question object instead? Perhaps you meant to write this:

alert(quiz.questions[0].choice0);
Robert Tyree
Robert Tyree
13,335 Points
Robert Tyree
Robert Tyree
13,335 Points

Thanks Steven! You nailed it.