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

Joseph Rimar
Joseph Rimar
17,101 Points
Posted by Joseph Rimar
Joseph Rimar
17,101 Points

Solution to quiz using a function?

Hey everyone. I used the same type of function Dave showed us in the previous videos to come up with a solution that seems to work just as well. I'm wondering what benefit there is to using Dave's suggested method instead of something like this if functions are normally the backbone of JavaScript? 

var quizQuestions = [
  ['How many days are there in a week?', '7'],
  ['What is the capital of England?', 'london'],
  ['What is the highest mountain on Earth?', 'everest'],
  ['What is the capital of Japan?', 'tokyo']
]


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

function answeredQuestions (questions) {
    var numberRight = 0;
    var correctListHTML = '<h2>You got these questions right:</h2>' + '<ol>';
    var incorrectListHTML = '<h2>You answered these questions wrong:</h2>' + '<ol>';

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

     var answers = prompt(questions[i][0]);
     if (answers === questions[i][1]) {
       correctListHTML += '<li>' + questions[i][0] + '</li>';
       numberRight ++;
     } else {
       incorrectListHTML += '<li>' +  questions[i][0] + '</li>' ;
     }
   }
  correctListHTML += '</ol>';
  incorrectListHTML += '</ol>';


  print('You got ' + numberRight + ' question(s) right.'); 
  print(correctListHTML);
  print(incorrectListHTML);
 }

answeredQuestions(quizQuestions);

1 Answer

Marcus Parsons
Marcus Parsons
15,719 Points
Marcus Parsons
Marcus Parsons
15,719 Points

Hey Joseph,

I believe that answers lies within what your ultimate goal of the code would be. You create functions for pieces of code that you want to run multiple times. Since this challenge was a stand alone program, there's really no need to create any functions for this program. And it is faster to use straight through code, instead of calling custom functions, as you can see in this JavaScript performance test: http://jsperf.com/custom-functions-vs-no-functions

Joseph Rimar
Joseph Rimar
17,101 Points
Joseph Rimar
Joseph Rimar
17,101 Points

Thanks Marcus, I thought that using as few variables as possible would actually be more efficient and I did not realize that using functions was actually slower.

Marcus Parsons
Marcus Parsons
15,719 Points

If you think about it, it's having to make more calls than it would if the code were straight through i.e. using print(message) it has to find the function print, pass in the values given, then find document.write() and pass in the values given, and execute it whereas if you just used document.write(), it would only need to find document.write() and then pass in the info and execute it.

I made a test case for your code versus a straight through version of your code, but evidently, document.write() messes with the performance operation. I'll make another one that uses alert() instead of document.write().

Marcus Parsons
Marcus Parsons
15,719 Points

Here is the performance test where your code was put into the top portion. The only part that was changed was instead of using document.write(), I used alert(). The bottom part uses the same variables, same questions, just in a straight through format. http://jsperf.com/custom-functions-vs-no-functions/2