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I recently discovered a bug in my JavaScript quiz by accident. It’s a multiple choice quiz. I clicked on one of the answers. Then I kept clicking submit through the questions until the quiz was done. Instead of saying that I got 1 out of 15 questions right it said I got like 6 of 15 right, even though I left the other questions blank. This error in calculation only happens when I keep clicking submit after choosing an option. Any assistance is appreciated.

var pos = 0, test, test_status, question, choice, choices, chA, chB, chC, correct = 0;
var questions = [
	["What does HTML stand for?", "High Tech Markup Language", "Hyper Text Multiple Listing", "Hyper Text Markup Language", "C"],
	["What does CSS stand for?", "Computer Software Supervisor", "Cascading Stylesheets", "Computer Software Systems", "B"],
	["What aspect of a website does JavaScript control?", "the behavior", "the structure", "the design & layout", "A"],
	["What are media queries for?","They give the programmer access to covert media files.", "They make websites function well and look great on multiple devices like tablets and smartphones.", "They're a set of javascript libraries...like jquery.", "B"],
	["The two categories of elements in html are block and...", "outline", "flatline", "inline", "C"],
	["Which data type gives a value of true or false?", "character", "boolean", "integer", "B"],
	["How do you write a comment in CSS?", "/* */", "//", "just write it out..", "A"],
	["Java was developed by which company?", "Netscape", "Sun Microsystems", "Enron", "B"],
	["Which gets more priority in CSS?", "class attribute", "element", "id attribute" ,"C"],
	["PHP is a _________ language.", "server-side", "client-side", "westside", "A"],
	["What does API stand for?", "Application Program Interface", "Apple Programs Iphones", "Advanced Programming Institute", "A"],
	["Wordpress is a ...", "Content Management Device", "Content Manipulating Stylesheet", "Content Management System", "C"],
	["Which of these is NOT a real programming language?", "C", "CSS", "JavaScript", "B"],
	["In an HTML document it's best to store javascript in the ____ of the page.", "head", "bottom of the body", "top of the body", "B"],
	["Bootstrap was built at which popular social media site?", "Twitter", "Facebook", "Instagram", "A"]
];
function _(x) {
	return document.getElementById(x);
}
function renderQuestion() {
	test = _("test");
	if(pos >= questions.length){
		test.innerHTML = "<h2>You got "+correct+" of "+questions.length+" questions correct</h2>";
		_("test_status").innerHTML = "Test Completed";
		pos = 0;
		correct = 0;
		return false;
	}
	_("test_status").innerHTML = "Question "+(pos+1)+" of "+questions.length;
	question = questions[pos][0];
	chA = questions[pos][1];
	chB = questions[pos][2];
	chC = questions[pos][3];
	test.innerHTML = "<h3>"+question+"</h3>";
	test.innerHTML += "<input type='radio' name='choices' value='A'> "+chA+"<br>";
	test.innerHTML += "<input type='radio' name='choices' value='B'> "+chB+"<br>";
	test.innerHTML += "<input type='radio' name='choices' value='C'> "+chC+"<br><br>";
	test.innerHTML += "<button onclick='checkAnswer()'>Submit Answer</button>";
}
function checkAnswer(){
	choices = document.getElementsByName("choices");
	for(var i=0; i<choices.length; i++){
		if(choices[i].checked){
			choice = choices[i].value;
		}
	}
	if(choice == questions[pos][4]){
		correct++;
	}
	pos++;
	renderQuestion();
}
window.addEventListener("load", renderQuestion, false);
body {
	background: #f5f5f5;
}
* {
	margin: 0;
	padding: 0;
}
header {
	width: 1000px;
	height: 190px;
	background-color: firebrick;
	margin: 0 auto;
	border-left: black solid 1px;
	border-right: black solid 1px;
	
}
h1 {
	color: white;
	text-align: center;
	position: relative;
	top: 65px;
	font-size: 3em;
	font-family: cooper;
}
h2 {
	position: relative;
	top: 30px;
	margin: 10px;
	padding: 10px 40px 40px 40px;
}
h3 {
	text-align: center;
	font-size: 2em;
}
h5 {
	color: white;
	text-align: center;
	font-size: 1.3em;
	position: relative;
	top: 110px;
}
p {
	text-align: center;
	font-size: 1.5em;
}
a {
	text-decoration: none;
}
section {
	width: 1000px;
	height: 700px;
	margin: 0 auto;
	background-color: white;
	border-left: black solid 1px;
	border-right: black solid 1px;
}
#center {
	text-align: center;
	position: relative;
	top: 20px;
}
#test {
	color: black;
	border: #000 1px solid;
	padding: 10px 40px 40px 40px;
	background-color: white;
	margin-left: 20px;
	margin-right: 20px;
	position: relative;
	top: 100px;
}
footer {
	width: 1000px;
	height: 250px;
	background-color: #003366;
	margin: 0 auto;
	border-left: black solid 1px;
	border-right: black solid 1px;
}
<!DOCTYPE html>
<html>
<head>
	<meta charset="UTF-8">
	<title>Web Developer Quiz</title>
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
	<div="it">
	<h2 id="test_status"></h2>
	<div id="test"></div>
	<button><a href="index.html"></a></button>
	</div>
	<script src="script.js"></script>
</body>
</html>

2

Answers


  1. In the beginning of your renderQuestion() function, you should reset your choice variable

    function renderQuestion() {
        choice = undefined;
        test = _("test");
        ...
    }
    
    Login or Signup to reply.
  2. You should declare the variable choice inside the checkAnswer() function instead of globally on the first line of your code. So make your global declarations look like this:

    var pos = 0, test, test_status, question, choices, chA, chB, chC, correct = 0;
    

    and then add it checkAnswer() like this:

    function checkAnswer(){
      var choice;
    ...
    
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