Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript JavaScript Loops, Arrays and Objects Tracking Multiple Items with Arrays Build a Quiz Challenge, Part 1

Ivan Kozhunkov
PLUS
Ivan Kozhunkov
Courses Plus Student 8,480 Points
Posted by Ivan Kozhunkov
Ivan Kozhunkov
Courses Plus Student 8,480 Points

Problems in my code....

Building a program with two dimensional arrays....

My code:

// Answers 

var questions = [
 ['Which corporation is an owner of Bentley', 'Volkswagen'],

['Which city is a capital of Japan', 'Tokio'],

['The Chevrolet\'s SUV and the lake in California', 'Tahoe'],

  ];


// variable for an answer        
var answer;              


// arrays for correctly and incorrectly results

var goodResult = [];

var badResult = [];



function print (message)

{
      document.write(message);
}




// choose only first elements of array questions


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

    answer += prompt ([i][0]);

}

Something error in the loop Uncaught TypeError: Cannot read property '0' of undefined

What I'm doing incorrectly?

Moderator edited: Added markdown so that the code will display properly on the forums.

Jennifer Nordell
seal-mask
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Hi Ivan! I added some markdown to your question so that the code will display properly and be more readable by other students. Check out the Markdown Cheatsheet link at the bottom of the "Add an Answer" section for tips on how to format your code/questions/answers! :sparkles:

1 Answer

Steven Parker
Steven Parker
229,771 Points
Steven Parker
Steven Parker
229,771 Points

You're attempting to index a scalar value.

In your expression "questions.length [i] [0]", the questions.length part by itself represents a numeric value (the number of questions). Then when you index it using "[i]", it will return undefined. Then trying to index that using "[0]" produces the error you see.

What you probably meant to write may have just been "questions.length".

Also, on the last line where you have "prompt([i][0])", you probably meant to write "prompt(questions[i][0])".