Introduction
A timed quiz refers to an online quiz that comes with a pre-defined time limit for completing it. It can serve different purposes ranging from educational assessments, and certification tests to fun-filled quizzes. Timed quizzes are great for keeping the participants engaged and providing them with a sense of urgency to complete the quiz within a specific timeframe. This feature makes timed quizzes more engaging and exciting for the participants.
The advantage of using JavaScript to create a timed quiz is that you can customize the quiz according to your requirements. For instance, you can set the quiz timer to any duration you prefer, and even display the time remaining to the participants. Also, JavaScript allows you to calculate the quiz score, validate the answers, and even provide feedback to the participants.
One significant benefit of creating a timed quiz using JavaScript is that you can reuse the code in creating additional quizzes. You only need to modify the questions, answers, and time limit, and the quiz is ready to go. This approach saves time and effort in creating new quizzes and allows you to provide your audience with different types of quizzes.
Challenges
The main challenge in creating a timed quiz is to display the remaining time and to end the quiz when the time limit is reached. This can be done using JavaScript’s set interval function, which runs a given function at a set interval until stopped. We will use this function to display the time remaining and to end the quiz when the time limit is reached.
To create a timed quiz, we need to do the following steps:
Define the questions and answers
The first step in creating a timed quiz is to define the questions and answers. This can be done by creating two arrays, one for the questions and one for the answers. You can also store the questions and answers in a database or external file for easier management.
let questions =
[
'What is the value of x in the equation 2x + 5 = 13?',
'Solve the equation 3(x + 2) = 18.',
'What is the value of y in the equation 5y - 7 = 18?',
'Solve the equation 2x - 3 = 7x + 1.',
'Simplify the expression 3(x - 4) - 2(2x + 1).'
];
let answers =
[
'4',
'4',
'5',
'-4/5',
'-x-14'
];Display the quiz questions
The next step is to display the quiz questions to the user. We use JavaScript to dynamically generate the questions and input fields on the page by using the arrays mentioned above.
for(let i = 0; i < questions.length; i++)
{
let questionlist = document.createElement('p');
let answerInput = document.createElement('input');
answerInput.type = 'text';
answerInput.name = 'answerInput';
answerInput.id = 'answerInput';
questionlist.textContent += (i + 1) + ')';
questionlist.textContent += questions[i] + ' ';
questionlist.appendChild(answerInput);
questionlist.className += 'questionItem';
questionsDisplay.appendChild(questionlist);
}This code creates a set of HTML elements dynamically using JavaScript to display the quiz questions and answer input fields on the web page.
First, a for loop is used to iterate through the array of quiz questions. Within the loop, two new HTML elements are created using the document.createElement method. The first element is a <p> tag to hold the question and the second is an <input> tag to allow users to enter their answer.
Next, the properties of the answer input element are set using the answerInput.type, answerInput.name, and answerInput.id properties. This sets the input type to text, assigns a name to the input element, and gives it a unique ID.
Then, the question number and text are appended to the question list element using the textContent property. The answer input field is then appended to the question list element using the appendChild method. Finally, a class is added to the question list element using the className property.
Lastly, the question list element is added to the web page by appending it to the questionsDisplay element using the appendChild method.
This process is repeated for each question in the questions array, creating a set of question and answer input fields dynamically on the web page.
This approach allows the code to be easily modified and reused by simply adding additional questions and answers to the questions and answers arrays.
Start the timer
To start the timer, we will use JavaScript’s set interval function. We will define a countdown function that will be called every second until the time limit is reached. Inside this function, we will display the remaining time and end the quiz when the time limit is reached.
function startTimer()
{
let clock = document.getElementById('clock');
let timerID = setInterval(countdown, 1000);
function countdown()
{
if(timeLeft === 0)
{
clearInterval(timerID);
alert('Time is up!');
calculateScore();
}
else
{
clock.value = timeLeft;
timeLeft--;
}
}
}The startTimer() function is responsible for creating a countdown timer for the quiz.
First, it gets the HTML element with the ID clock and assigns it to the clock variable. Then it creates a timerID variable and assigns it to the result of the setInterval() function. The setInterval() function takes two arguments: the function countdown() and the time interval in milliseconds (in this case, 1000 milliseconds or 1 second).
The countdown() function is then defined within the startTimer() function. It checks if the timeLeft variable is equal to 0. If it is, then it stops the timer by calling clearInterval() with the timerID variable as an argument. It then displays an alert message that says “Time is up!” and calls the calculateScore() function.
If timeLeft is not equal to 0, then the timer is still running. The current value of timeLeft is displayed in the clock element by assigning it to the value property of clock. Then, timeLeft is decremented by 1 to indicate that 1 second has passed.
By using setInterval(), the countdown() function will be called every 1 second until the timer is stopped. This creates a continuous countdown effect, making the timed quiz more engaging and exciting for participants.
Calculate the score
Once the user has completed the quiz or the time limit has been reached, we will calculate the user’s score. We can do this by comparing the user’s answers to the correct answers stored in the array. We can then display the user’s score to the user.
function calculateScore()
{
let score = 0;
let answerInputs = document.querySelectorAll('input[name="answerInput"]');
for(let i = 0; i < answerInputs.length; i++)
{
if(answerInputs[i].value === answers[i])
{
score++;
}
}
alert("You're score is " + score + ' out of ' + answers.length);
questionsDisplay.innerHTML = '';
document.getElementById('clock').remove();
document.getElementById('startquiz').remove();
quizStarted = false;
let label = document.querySelectorAll('label');
label[0].textContent = 'Thank you for taking the quiz.';
}The calculateScore function is responsible for calculating and displaying the score of the quiz once the time limit has been reached.
The function begins by declaring a variable score and setting it to 0. It then selects all the input elements with the name “answerInput” using the querySelectorAll method and assigns them to a variable called answerInputs.
The function then uses a for loop to loop through each of the answer inputs and compare the value entered by the user to the corresponding answer in the answers array. If the user’s answer matches the correct answer, the score variable is incremented.
Once all the answers have been checked, an alert is displayed showing the user’s score and the total number of questions.
Finally, the questionsDisplay element is cleared by setting its innerHTML to an empty string. The timer and start button are removed from the page by calling the remove method on their respective elements. The quizStarted variable is set back to false.
Lastly, the function selects all the label elements on the page and changes the text content of the first one to “Thank you for taking the quiz.”
End the quiz
After the user has completed the quiz or the time limit has been reached, we will end the quiz. We can do this by removing the quiz questions and input fields from the page.
One of the advantages of using JavaScript to create a timed quiz is that the code can be easily reused for future quizzes. You can simply update the questions and answers in the arrays and generate new quiz questions and input fields using the existing code.
See my Code:
JavaScript_Short_Projects/Timed_quiz at main · michellealzola/JavaScript_Short_Projects (github.com)
See the Site in Action:
Timed Quiz (michellealzola.github.io)
Conclusion
A timed quiz is an engaging and exciting way to test a user’s knowledge. By using JavaScript’s set interval function, we can create a timed quiz that displays the remaining time and ends the quiz when the time limit is reached.
