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JavaScript

Posted by David Drysdale
David Drysdale
10,815 Points

Quiz part works, but final message does not display

When I run my code, I am prompted for each question and the program correctly tells me whether my answer was right or not.

However, the console is reporting the following error; plus, the final message -- print(html) -- is not displaying.

Uncaught TypeError: Cannot read property '0' of undefined(anonymous function) @ quiz.js:17

Can somebody help me debug this?

var score = 0;
var response;
var html;

var questions = [
  ["What is the capital of New York State?", "albany"],
  ["What is the capital of Washington State?", "olympia"],
  ["What is the capital of California?", "sacremento"]
];    

function print(message) {
  document.write(message);
}

for(var i = 0; i <= questions.length; i+=1) {

  response = prompt(questions[i][0]);

  if (response.toLowerCase() === questions[i][1]) {
    score +=1;
    alert("That's correct!");

  } else {
    alert("No, sorry. That's incorrect.");
  }

}

html = "You scored " + score + " points.";
print(html);

1 Answer

Ethan Weeks
Ethan Weeks
15,352 Points

The variable questions is undefined because the for loop is running one extra time after it has looped through all the array index's. 

// i = 3; i <= 3  true 

for(var i = 0; i < questions.length; i+=1) {

  response = prompt(questions[i][0]);

  if (response.toLowerCase() === questions[i][1]) {
    score +=1;
    alert("That's correct!");

  } else {
    alert("No, sorry. That's incorrect.");
  }

}