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

edmond habimana
PLUS
edmond habimana
Courses Plus Student 8,352 Points
Posted by edmond habimana
edmond habimana
Courses Plus Student 8,352 Points

Can some check my code. I want to know what i did wrong.

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


var quiz = [
    ["how many states are in the USA?", 50],
    ["what is 2 + 2 = ?", 4],
    ["what is 6 + 6= ?", 12],
    ["what is 7 + 7= ?", 14],
    ["what is 4 + 4= ?", 8]
]
var answerCorrect = 0;
var questionCorrect;
var questionWrong;
var questions;

for(var i=0; i <= quiz.length; i++){
    questionCorrect = "<h2> quetions you got right.</h2><br/>";
    questionWrong = "<h2> quetions you got wrong.</h2><br/>";
    questions = prompt(quiz[i][0]);
    var answers = parseInt(questions);
    if (answers === quiz[i][1]){
        answerCorrect += 1;
        questionCorrect += "<p>" +quiz[i][0]+ "</p><br/>";
    }else{
        questionWrong += "<p>" +quiz[i][0]+ "</p><br/>";
    }
}
    print("this is how many quetions you got right: "+answerCorrect);
    print(questionCorrect);

    print(questionWrong);

2 Answers

Erik Nuber
Erik Nuber
20,629 Points
Erik Nuber
Erik Nuber
20,629 Points

One of the issues you are having is that you reset questionsCorrect and questionsWrong every time you go thru the for loop.

for(var i=0; i <= quiz.length; i++){
    questionCorrect = "<h2> quetions you got right.</h2><br/>";
    questionWrong = "<h2> quetions you got wrong.</h2><br/>";
    questions = prompt(quiz[i][0]);
    var answers = parseInt(questions);
    if (answers === quiz[i][1]){
        answerCorrect += 1;
        questionCorrect += "<p>" +quiz[i][0]+ "</p><br/>";
    }else{
        questionWrong += "<p>" +quiz[i][0]+ "</p><br/>";
    }
}

With the way this loop is set up, each time the variable i is incremented and the loop is run through, questionsCorrect and questionsWrong are set to "<h2> quetions you got right.</h2><br/>"; and "<h2> quetions you got wrong.</h2><br/>";.

so moving them out like this will keep them from resetting.

var answerCorrect = 0;
var questionCorrect  = "<h2> questions you got right.</h2><br/>";
var questionWrong = "<h2> questions you got wrong.</h2><br/>";
var questions;
var answers;

for(var i=0; i <= quiz.length; i++){
    questions = prompt(quiz[i][0]);
    answers = parseInt(questions);
    if (answers === quiz[i][1]){
        answerCorrect += 1;
        questionCorrect += "<p>" +quiz[i][0]+ "</p><br/>";
    }else{
        questionWrong += "<p>" +quiz[i][0]+ "</p><br/>";
    }
}

next, in the for loop, you are giving a comparison operator that is pulling an undefined.

i <= quiz.length

this will mean that the final time the loop runs, you aren't actually giving the questions anything

i < quiz.length

will fix the issue as remember that the index value starts at 0 and goes up to one less than the length of the array.

you could also fix this by doing

i <= (quiz.length -1)

which is the same thing.

edmond habimana
PLUS
edmond habimana
Courses Plus Student 8,352 Points
edmond habimana
edmond habimana
Courses Plus Student 8,352 Points

Thank a lot Erik, i really appreciate you taking your time checking my code and explaining what i did wrong. I am new at javascript and these silly mistakes were starting to drive me crazy.

Erik Nuber
Erik Nuber
20,629 Points
Erik Nuber
Erik Nuber
20,629 Points

It's not silly mistakes. You are more than fine. It is apart of the learning process. You will find mistakes constantly when you are coding and, it is learning how to find them that will benefit you the most. So no need to apologize or explain. Best of luck as you continue the course.