javascript online test with code examples

JavaScript is a powerful object-oriented programming language that allows developers to create interactive and dynamic websites. If you are a web developer, it is essential to have a sound knowledge of JavaScript and practice it regularly to enhance your skills. One way to test your JavaScript skills is by taking online tests. In this article, we will explore some of the best JavaScript online tests that are available and provide code examples to help you prepare.

  1. Codecademy

Codecademy is one of the most popular online coding education platforms, and it offers a wide range of courses, including JavaScript. Codecademy has a series of JavaScript quizzes and tests that can help you check your progress and skills.

Codecademy's JavaScript quizzes allow you to test your knowledge of different JavaScript concepts, including variables, functions, loops, and arrays. They also have a set of JavaScript projects that allow you to practice your coding skills by developing real-world apps.

Here are some examples of their quizzes:

a) What is the output of the following code?

let x = 10; 
let y = "5"; 
console.log(x + y);

Answer: 105

b) What is the output of the following code?

let x = 10;
if(x === "10"){
} else {
  console.log("Not Equal");

Answer: Not Equal

  1. HackerRank

HackerRank is an online coding platform that offers competitive programming challenges and tests. It has a wide range of JavaScript tests, from beginner-level tests to advanced-level tests.

HackerRank's JavaScript tests cover a wide range of topics, including arrays, recursion, sorting, and string manipulation. You can take the tests anytime and see your score immediately.

Here are some examples of their tests:

a) Write a JavaScript function that returns the sum of all positive numbers in an array

function sumOfPositives(array) {
  let sum = 0;
  for(let i = 0; i < array.length; i++){
    if(array[i] > 0){
      sum += array[i];
  return sum;

b) Write a JavaScript function that reverses a string

function reverseString(string) {
  let reversed = "";
  for(let i = string.length -1 ; i >= 0; i--){
    reversed += string[i];
  return reversed;
  1. FreeCodeCamp

FreeCodeCamp is a non-profit organization that offers free coding education to anyone who wants to learn to code. It has a comprehensive JavaScript curriculum that covers a wide range of topics, including the basics of JavaScript, object-oriented programming, and data structures.

FreeCodeCamp has a set of JavaScript quizzes that can help you test your knowledge of different JavaScript concepts. Its curriculum also includes projects that allow you to practice writing code and develop real-world applications.

Here are some examples of their quizzes:

a) What will be the output of the following code?

let array1 = [1, 2, 3];
let array2 = array1;
array1[0] = 0;

Answer: 0

b) What is the difference between let and var in JavaScript?

Answer: var is function-scoped, while let is block-scoped.

  1. JavaScript Quiz

JavaScript Quiz is a dedicated website that offers a vast library of JavaScript tests. It has a range of tests for beginners, intermediate-level, and advanced-level coders.

JavaScript Quiz offers multiple-choice questions, true/false questions, and coding challenges. You can take their tests online and see the results immediately.

Here are some code examples:

let arr = [1, 2, 3, 4, 5];
let sum = arr.reduce(function(a, b) {
  return a + b;

Answer: 15

let x = 10;
if(x === 10){
  let y = 5;

Answer: ReferenceError: y is not defined


JavaScript online tests are an excellent way to practice and enhance your skills. They allow you to check your progress and identify areas where you need to improve. By taking JavaScript tests, you can gain confidence in your skills as a coder. We hope this article has provided you with some useful JavaScript code examples and useful information about the different online tests available. Happy coding!

let's dive in and explore in more detail some of the topics that we touched on in the previous article.


Codecademy is known for its interactive online coding education platform, which provides courses in various programming languages. It is a great platform for beginners seeking to start their coding journey, but it also provides advanced courses suitable for professionals seeking to expand their skills.

In addition to its courses, Codecademy also offers a set of JavaScript quizzes that are specifically designed to test your knowledge of different concepts within the JavaScript language. These quizzes cover topics such as functions, arrays, loops, and objects and are perfect for testing your knowledge of the basics.

Codecademy also features JavaScript projects that put your knowledge to the test and allow you to practice by building real-world applications. These projects include building a meal-making robot, implementing a weather app, and building a quiz game.


HackerRank is another popular online coding platform. It is considered a competitive programming platform that features coding contests and challenges. It has a vast library of coding problems to solve, including many different challenges within JavaScript.

One of the benefits of practicing JavaScript on HackerRank is that its problems and challenges are graded based on difficulty level. This grading system allows you to start at your level of experience and practice at your own pace.

HackerRank's JavaScript challenges cover a wide range of concepts, including data structures, algorithms, and regular expressions. Solving these challenges will help you build your problem-solving and JavaScript skills, making you a better developer.


FreeCodeCamp is a non-profit organization that offers free coding education to anyone worldwide. Its curriculum is extensive and includes a range of programming languages such as JavaScript, HTML, CSS, and more.

The FreeCodeCamp JavaScript curriculum starts at the basic concepts and ends with creating full-stack applications. It is structured in a way that allows you to learn at your own pace, with challenging quizzes and coding projects that test your knowledge and build your skills.

One of the unique features of FreeCodeCamp is that it focuses on developing real-world skills. Its coding projects are created to match the needs and requirements of companies and organizations. By completing these projects, you gain practical experience and knowledge that is useful when applying for jobs in the tech industry.

JavaScript Quiz

JavaScript Quiz is a website dedicated entirely to JavaScript tests. Its quizzes are suitable for beginners, intermediate-level coders, and advanced users.

One of the unique features of JavaScript Quiz is that it offers a range of question types, such as multiple-choice, true/false, and coding challenges. This variety allows you to test your knowledge from different angles and challenge yourself.

The JavaScript coding challenges at JavaScript Quiz are particularly useful in that they allow you to test your ability to write functioning code. By solving these coding challenges, you can put your coding skills to the test and get immediate feedback on your code.


In conclusion, these JavaScript online tests are a great resource for anyone looking to learn or improve their JavaScript skills. Whether you're a beginner or an experienced developer, testing your knowledge is an essential part of the learning process. These tests are specially designed to cover a range of topics and concepts within JavaScript, from the basics to advanced coding challenges. So, take advantage of these resources and start testing your skills today!

Popular questions

Sure, here are five JavaScript questions with answers:

  1. What is the output of this code?
let a = 3;
let b = 5;
let c = a + b;
console.log(c * 2);

Answer: 16

  1. What is the difference between a for loop and a while loop in JavaScript?
    Answer: A for loop is used when you know the number of times you want to execute the loop. A while loop is used when you want to repeat something until a condition is met.

  2. What is the difference between null and undefined in JavaScript?
    Answer: null means no value, and it is an explicit value that you can set for a variable. undefined means that a variable has been declared, but it has not been assigned a value.

  3. How would you add a new element to the end of an array in JavaScript?
    Answer: You can use the push() method to add a new element to the end of an array. For example:

let arr = [1, 2, 3];
  1. Write a function that returns the factorial of a number (recursive).
function factorial(n) {
  if (n === 0) {
    return 1;
  } else {
    return n * factorial(n - 1);



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