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

Posted by Eric Conklin
Eric Conklin
8,350 Points

Quiz challenge from arrays javascript section

/*Variables*/

var questionAnswer = [
  ['Who is the president?', 'Barack Obama'],
  ['What is the 3rd month of the year?', 'March'],
  ['What color is the sky?', 'Blue']
]
var questionsRight;
var questionsRightList;
var questionsWrong;
var questionsWrongList;
var answer1 = prompt(questionAnswer[0][0]);
var answer2 = prompt(questionAnswer[1][0]);
var answer3 = prompt(questionAnswer[2][0]);
var answer1Right;
var answer2Right;
var answer3Right;
var answer1Wrong;
var answer2Wrong;
var answer3Wrong;

/* If else loops for answers */

  if (answer1 = questionAnswer[0][1]){
    var questionsRight += 1;
    var answer1Right = questionAnswer[0][0];
  } else {
    var questionsWrong += 1;
    var answer1Wrong = questionAnswer[0][0];
  }

  if (answer2 = questionAnswer[1][1]){
    var questionsRight +=1;
    var answer2Right = questionAnswer[1][0];
  } else {
    var questionsWrong += 1;
    var answer2Wrong = questionAnswer[1][0];
  }

  if (answer3 = questionAnswer[2][1]){
    var questionsRight +=1;
    var answer3Right = questionAnswer[2][0];
  } else {
    var questionsWrong += 1;
    var answer3Wrong = questionAnswer[2][0];
  }

var questionsRightList = [answer1Right, answer2Right, answer3Right];
var questionsWrongList = [answer1Wrong, answer2Wrong, answer3Wrong];

Unexpected token at line 25. What is wrong with the += operator the way I'm using it? Help...

3 Answers

elk6
elk6
22,916 Points
elk6
elk6
22,916 Points

Hi Eric,

You are declaring your var over and over. You only need to use the var keyword for the first time you delcare it. When changing the value you only need to write it's name followed by += ( in this case ).

Also, if you put your code inside 3 backticks ( ) your code will be a lot easier to follow on the forum. So 3 times in front and 3 times ` at the back of your code.

Hope this helps.

Colin Bell
Colin Bell
29,679 Points
Colin Bell
Colin Bell
29,679 Points

I made the code a little easier to read.

Eric Conklin
Eric Conklin
8,350 Points
Eric Conklin
Eric Conklin
8,350 Points

Elian, it was my understanding that in order to access a global variable, I had to redeclare it within the for loop. Is this incorrect?

Colin Bell
Colin Bell
29,679 Points
Colin Bell
Colin Bell
29,679 Points

it was my understanding that in order to access a global variable, I had to redeclare it within the for loop. Is this incorrect?

Nope. A global variable is accessible anywhere. So you can declare it once in the global scope, then use it in any loop, function, array, etc.

You're also doing a lot of work that a for loop can do for you. You don't need to declare a variable for each separate question in the global scope. Plus, if you were to add more questions to your array, you'd have to keep adding variables for questionsRight, questionsWrong, etc.

The global variables you need to declare are :

  • The questions variable with your questions and answers
  • Setting your initial questionsRight and questionsWrong variables to 0.
  • Setting questiongsRightList & questiongsWrongList to empty arrays.
var questions  = [
  ['Who is the president?', 'Barack Obama'],
  ['What is the 3rd month of the year?', 'March'],
  ['What color is the sky?', 'Blue']
];

var questionsRight = 0;
var questionsWrong = 0;
var questionsRightList = [];
var questionsWrongList = [];

/* Don't NEED to declare the following right away, but it's good practice to go ahead
and declare the variables you're going to use. Notice you don't need to assign any
default value to them */
var question;
var answer;
var response;
var html;

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

for (var i=0; i < questions.length; i++) {
  // Get the first item from array[i] and set it as question
  question = questions[i][0];

  // Get the second item from array[i] and set it as answer
  answer = questions[i][1];

  // Get input from the user and set it to the response variable
  response = prompt(question);

  if (response === answer) {
    //questionsRight is initially 0. If response === answer questionsRight = 0+1
    questionsRight += 1;
    // Push the question into the questionsRightList array if answered correctly. 
    questionsRightList.push(question);
  }
  else {
    //questionsWrong is initially 0. If response === answer questionsWrong = 0+1
    questionsWrong += 1;
    // Push the question into the questionsRightList array if answered correctly. 
    questionsWrongList.push(question);
  }
}

print(questionsRight + " " + questionsRightList + "; " + questionsWrong + " " + questionsWrongList );