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


Bodie Wood
Bodie Wood
Full Stack JavaScript Techdegree Student 4,027 Points

Simple solution.

const quiz = [['What is a Sheepadoodle?','Is a tomato a fruit or veggie?', 'Are birds real?'],
              ['dog', 'fruit', 'yes']];

let numCorrect = 0;

for(i = 0; i <= quiz.length; i++){
  const answer = prompt(`${quiz[0][i]}`).toLowerCase();
  if(answer === quiz[1][i]){

document.querySelector('main').innerHTML = `<h1>You answered ${numCorrect} questions correct.`;

Good work.

In the for statement, you are using i = 0 and what that does, with no let, const or even the lesser used var, is set i = 0 against the global object.

In the browser, that is window in the browser, and global in nodejs.

This would mean that if something else in the global namespace had set the value for i already, your loop has just overwritten it. You can scope the variable to just the for loop by changing it to let i = 0.