JavaScript Quiz for Beginners: Test Your Knowledge

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If you’re looking to test your knowledge and skills in JavaScript, you’ve come to the right place. This quiz is designed for those who are just starting their programming journey and want to see how well they understand the fundamentals of JavaScript.

Whether you’re a student, a self-learner, or just curious about the language, this quiz is a great way to challenge yourself and learn along the way.

What You’ll Learn

Our JavaScript quiz will cover a range of topics, including basic concepts like variables, data types, and operators. It will also touch on more advanced topics such as functions, loops, and error handling.

Each question is carefully crafted to ensure that it tests your understanding while also helping you learn from the explanations provided.

Why Take a JavaScript Quiz?

Taking a quiz can be an excellent way to reinforce your knowledge. It helps you identify the areas where you need more practice and boosts your confidence when you answer correctly.

Quizzes also offer a fun way to engage with what you’ve learned, making it easier to remember key points and apply them in real-world projects.

How to Play This JS Quiz for Beginners

This JavaScript quiz for beginners is straightforward. Each question is followed by multiple-choice answers, with only one correct option.

After you have attempted all questions, you will get the results, showing your score and areas for improvement. Take your time, and don’t rush—each question is an opportunity to learn.

So, get ready to test your knowledge and see how well you know JavaScript. It’s a great way to challenge yourself, improve your coding skills, and build a strong foundation in this powerful programming language. Good luck!

  • Question of

    What is JavaScript?

    • A programming language for adding interactivity to web pages
    • A database management tool
    • A markup language like HTML
    • A server-side programming language only

    Correct Wrong

    Correct Answer: A. A programming language for adding interactivity to web pages Explanation: JavaScript is used for dynamic behavior on websites, such as animations and interactive forms.

  • Question of

    Which keyword is used to declare a variable in JavaScript?

    • var
    • let
    • const
    • All of the above

    Correct Wrong

    Correct Answer: D. All of the above Explanation: JavaScript allows variable declarations using var, let, and const. Each has different scoping rules and use cases.

  • Question of

    What is the output of the following code?

    javascript quiz for beginners question output code
    • “null”
    • “undefined”
    • “object”
    • “string”

    Correct Wrong

    Correct Answer: C. "object" Explanation: In JavaScript, null is considered an object type due to a historical bug in the language.

  • Question of

    Which of these is not a valid JavaScript data type?

    • String
    • Number
    • Character
    • Undefined

    Correct Wrong

    Correct Answer: C. Character Explanation: JavaScript does not have a Character data type. Strings represent text in JavaScript.

  • Question of

    What is the purpose of isNaN() function in JavaScript?

    • To check if a value is null
    • To check if a value is NaN
    • To check if a value is undefined
    • To convert a string to a number

    Correct Wrong

    Correct Answer: B. To check if a value is NaN Explanation: The isNaN() function determines whether a value is "Not-a-Number".

  • Question of

    Which of the following is a valid comment in JavaScript?

    • * This is a comment *
    • // This is a comment
    • All of the above

    Correct Wrong

    Correct Answer: B. // This is a comment Explanation: JavaScript uses // for single-line comments and /* */ for multi-line comments.

  • Question of

    What will typeof [] return in JavaScript?

    • “object”
    • “array”
    • “list”
    • “undefined”

    Correct Wrong

    Correct Answer: A. "object" Explanation: Arrays in JavaScript are a type of object.

  • Question of

    What is the difference between == and === in JavaScript?

    • Both are identical
    • == checks value, while === checks value and type
    • == checks type, while === checks value
    • None of the above

    Correct Wrong

    Correct Answer: B. == checks value, while === checks value and type Explanation: == allows type coercion; === does not.

  • Question of

    Which company developed JavaScript?

    • Google
    • Microsoft
    • Netscape
    • Sun Microsystems

    Correct Wrong

    Correct Answer: C. Netscape Explanation: Netscape developed JavaScript in 1995.

  • Question of

    Which of the following values is considered “falsy” in JavaScript?

    • 0
    • “false”
    • []
    • {}

    Correct Wrong

    Correct Answer: A. 0 Explanation: Falsy values in JavaScript include 0, "", null, undefined, NaN, and false.

  • Question of

    How do you define a function in JavaScript?

    • def functionName() {}
    • function functionName() {}
    • func functionName() {}
    • All of the above

    Correct Wrong

    Correct Answer: B. function functionName() {} Explanation: Functions in JavaScript are defined using the function keyword.

  • Question of

    What does the === operator compare?

    • Value only
    • Reference only
    • Value and type
    • None of the above

    Correct Wrong

    Correct Answer: C. Value and type Explanation: The === operator performs strict equality, comparing both value and type.

  • Question of

    Which of these keywords is used to handle errors in JavaScript?

    • throw
    • catch
    • try
    • All of the above

    Correct Wrong

    Correct Answer: D. All of the above Explanation: try, catch, and throw are used for exception handling in JavaScript.

  • Question of

    Which method can be used to remove the last element of an array in JavaScript?

    • shift()
    • pop()
    • remove()
    • slice()

    Correct Wrong

    Correct Answer: B. pop() Explanation: The pop() method removes the last element from an array and returns it.

  • Question of

    What is the correct way to write an if statement in JavaScript?

    • if i == 5 then
    • if (i == 5)
    • if i = 5
    • if (i === 5) then

    Correct Wrong

    Correct Answer: B. if (i == 5) Explanation: JavaScript requires parentheses for conditions in an if statement.

  • Question of

    How can you add a new element to the beginning of an array?

    • push()
    • unshift()
    • append()
    • insert()

    Correct Wrong

    Correct Answer: B. unshift() Explanation: The unshift() method adds one or more elements to the start of an array.

  • Question of

    What is the result of 2 ** 3 in JavaScript?

    • 6
    • 8
    • 9
    • 12

    Correct Wrong

    Correct Answer: B. 8 Explanation: The ** operator performs exponentiation, equivalent to Math.pow(2, 3).

  • Question of

    How do you write a loop in JavaScript?

    • for (i < 5; i++)
    • for (let i = 0; i < 5; i++)
    • for (let i = 0; i++)
    • for i to 5

    Correct Wrong

    Correct Answer: B. for (let i = 0; i < 5; i++) Explanation: A for loop in JavaScript requires initialization, condition, and iteration expressions.

  • Question of

    What does console.log() do in JavaScript?

    • Prints output to the browser console
    • Prompts the user for input
    • Writes to a file
    • Stops the program execution

    Correct Wrong

    Correct Answer: A. Prints output to the browser console Explanation: The console.log() method is used for debugging and logging information to the console.

  • Question of

    Which operator is used to concatenate strings in JavaScript?

    • +
    • &
    • ++
    • concat()

    Correct Wrong

    Correct Answer: A. + Explanation: The + operator concatenates strings in JavaScript.

  • Question of

    What is the result of typeof NaN?

    • “number”
    • “NaN”
    • “undefined”
    • “object”

    Correct Wrong

    Correct Answer: A. "number" Explanation: NaN is a special numeric value indicating "Not-a-Number".

  • Question of

    How do you declare an arrow function in JavaScript?

    • () => {}
    • function => {}
    • -> {}
    • => function {}

    Correct Wrong

    Correct Answer: A. () => {} Explanation: Arrow functions use the => syntax.

  • Question of

    What does the setTimeout() function do?

    • Executes code repeatedly after a delay
    • Delays code execution by a set time
    • Stops program execution
    • Clears an interval

    Correct Wrong

    Correct Answer: B. Delays code execution by a set time Explanation: The setTimeout() function executes code after a specified time.

  • Question of

    What does JSON.stringify() do in JavaScript?

    • Converts a JSON string into an object
    • Converts an object into a JSON string
    • Converts an array into a JSON object
    • Parses a JSON string

    Correct Wrong

    Correct Answer: B. Converts an object into a JSON string Explanation: JSON.stringify() serializes a JavaScript object into a JSON string.

  • Question of

    Which method is used to check if a string starts with a specific character?

    • endsWith()
    • startsWith()
    • charAt()
    • substring()

    Correct Wrong

    Correct Answer: B. startsWith() Explanation: The startsWith() method checks if a string begins with a specified character or substring.

  • Question of

    Which statement is true about null and undefined in JavaScript?

    • Both represent the same thing
    • null means no value, and undefined means a variable is declared but not initialized
    • null is used for functions, and undefined is for objects
    • null is a string, and undefined is a number

    Correct Wrong

    Correct Answer: B. null means no value, and undefined means a variable is declared but not initialized Explanation: null is explicitly set to indicate no value; undefined is the default for uninitialized variables.

  • Question of

    How do you write a promise in JavaScript?

    • promise = () => { … }
    • new Promise((resolve, reject) => { … })
    • Promise(() => { … })
    • None of the above

    Correct Wrong

  • Question of

    What is the default value of this in a JavaScript function?

    • The global object
    • null
    • undefined
    • The function itself

    Correct Wrong

    Correct Answer: A. The global object Explanation: In non-strict mode, the default value of this in a function is the global object (window in browsers).

  • Question of

    How do you convert a string to an integer in JavaScript?

    • parseInt()
    • parseFloat()
    • Number()
    • All of the above

    Correct Wrong

    Correct Answer: A. parseInt() Explanation: The parseInt() function converts a string into an integer.

  • Question of

    Which method adds one or more elements to the end of an array?

    • push()
    • pop()
    • unshift()
    • slice()

    Correct Wrong

    Correct Answer: A. push() Explanation: The push() method appends elements to the end of an array.

  • Question of

    How do you write an asynchronous function in JavaScript?

    • function async() {}
    • async function myFunction() {}
    • function myFunction() async {}
    • None of the above

    Correct Wrong

    Correct Answer: B. async function myFunction() {} Explanation: The async keyword is used to define asynchronous functions.

  • Question of

    What does the finally block do in JavaScript?

    • Executes code after a try-catch block regardless of the outcome
    • Executes code only if there’s no error
    • Skips execution when an error occurs
    • Stops program execution

    Correct Wrong

    Correct Answer: A. Executes code after a try-catch block regardless of the outcome Explanation: The finally block runs after try and catch, even if an exception is thrown.

  • Question of

    What does the typeof operator return for arrays?

    • “array”
    • “object”
    • “list”
    • “collection”

    Correct Wrong

    Correct Answer: B. "object" Explanation: Arrays are a subtype of objects in JavaScript.

  • Question of

    What does Object.keys() do in JavaScript?

    • Returns all keys of an object
    • Returns all values of an object
    • Returns the key-value pairs of an object
    • None of the above

    Correct Wrong

    Correct Answer: A. Returns all keys of an object Explanation: Object.keys() returns an array of an object's own property keys.

  • Question of

    Which method is used to parse JSON strings into JavaScript objects?

    • JSON.parse()
    • JSON.stringify()
    • parseJSON()
    • JSON.convert()

    Correct Wrong

    Correct Answer: A. JSON.parse() Explanation: The JSON.parse() method converts JSON strings into JavaScript objects.

  • Question of

    What is the use of Promise.all()?

    • To execute a single promise
    • To wait for all promises to resolve or any one to reject
    • To create a new promise
    • None of the above

    Correct Wrong

    Correct Answer: B. To wait for all promises to resolve or any one to reject Explanation: Promise.all() resolves when all promises pass or rejects on the first failure.

  • Question of

    What will this code output?

    js quiz for beginners what will be the output
    • true
    • false
    • Error
    • undefined

    Correct Wrong

    Correct Answer: B. false Explanation: The typeof operator returns "undefined" for undefined and "object" for null.

  • Question of

    What will be the output of this JavaScript code?

    js quiz code output question
    • 2
    • 3
    • 4
    • Error

    Correct Wrong

    Correct Answer: B. 3 Explanation: Sets store unique values, so duplicate 2 is ignored.

  • Question of

    What is the scope of a variable declared with var, let, and const?

    • var has block scope, let and const have function scope
    • var has function scope, let and const have block scope
    • var, let, and const all have block scope
    • var, let, and const all have global scope

    Correct Wrong

    Correct Answer: B. var has function scope, let and const have block scope Explanation: Variables declared with var are function-scoped, while let and const are block-scoped, meaning they are only accessible within the block where they are defined.

  • Question of

    What is the purpose of the try…catch statement in JavaScript?

    • To create a loop that runs indefinitely
    • To handle exceptions or errors that occur in the code block
    • To define a function
    • To declare a variable

    Correct Wrong

    Correct Answer: B. To handle exceptions or errors that occur in the code block Explanation: The try...catch statement allows you to execute code that might throw an error and catch that error to handle it gracefully without crashing the application.

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