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JavaScript JavaScript Loops, Arrays and Objects Tracking Multiple Items with Arrays Build a Quiz Challenge, Part 2 Solution

Posted by Jared Sanders
Jared Sanders
6,461 Points

Why does this code not work vs this code that does?

Hi there, I have two pieces of code that should do the same thing. The first code does not use a question and answer variable to store the prompt() first, and for some reason, returns undefined when trying to push to both incorrectArr and correctArr.. The second (commented out) code works as expected. Why does one code work but the other not? 

//Not Workng Code
var correctArr = [];
var correctList = "<ol>";
var incorrectArr = [];
var incorrectList = "<ol>";
var userInput;
var myArr = [
    ['What is 2 + 2?', 4],
    ['How many states are in the United States?', 50],
    ['What year is your mustang?', 2003]    
];

for (var i = 0; i < myArr.length; i += 1) {
    userInput = prompt(myArr[i][0]);
    userInput = parseInt(userInput);

    console.log(userInput === myArr[i][1]);

    if(userInput === myArr[i][1]) { //if userinput equals the current answer
        correctArr.push(myArr[i][0]);
        console.log(correctArr[i]);
        correctList += "<li>" + correctArr[i] + "</li>";
    } else {
        incorrectArr.push(myArr[i][0]);
        console.log(incorrectArr[i]);
        incorrectList += "<li>" + incorrectArr[i] + "</li>";
    }
}

document.write("<h2>Questions answered correctly:</h2>" + correctList + "</ol><h2>Questions answered incorrectly:</h2>" + incorrectList + "</ol>");


/*
//Working Code

var question;
var answer;
var correctArr = [];
var correctList = "<ol>";
var incorrectArr = [];
var incorrectList = "<ol>";
var userInput;
var myArr = [
    ['What is 2 + 2?', 4],
    ['How many states are in the United States?', 50],
    ['What year is your mustang?', 2003]    
];

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

    userInput = prompt(question);
    userInput = parseInt(userInput);

    console.log(userInput === answer);

    if(userInput === answer) { //if userinput equals the current answer
        correctArr.push(question);
        console.log(correctArr[i]);
        correctList += "<li>" + question + "</li>";
    } else {
        incorrectArr.push(question);
        console.log(incorrectArr[i]);
        incorrectList += "<li>" + question + "</li>";
    }
}

document.write("<h2>Questions answered correctly:</h2>" + correctList + "</ol><h2>Questions answered incorrectly:</h2>" + incorrectList + "</ol>");
*/

1 Answer

john larson
john larson
16,594 Points
john larson
john larson
16,594 Points

It's kinda odd. I copy and pasted. Got an error for the very last line. There was an extra }. I commented that out and it worked fine. The odd thing this that extra brace doesn't show up just looking at your code here on the page. Maybe see if you left an extra brace at the bottom and comment it out like I did.