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With tech giants like Uber, Netflix, Google, Microsoft, and many more leveraging the power of JavaScript, front-end developers are expected to be well-versed in the language. JavaScript MCQs for front-end developers are a must-know for tech aspirants aiming for this role.
JavaScript is the most used programming language, with 63.61% of the developers using it worldwide. There are innumerable opportunities available for developers with JavaScript basics and advanced understanding, but still, extensive effort is required to grab a job as a front-end developer. A strong understanding of the fundamentals, JavaScript basics, and ES6 MCQs is a commonly recommended expert tip.
Aiding you in the process of landing your dream job at the top-tech company, developing confidence, going through MCQs, and revision is helpful. Thus, here we bring you a collection of the most asked JavaScript MCQs for front-end developers and JS interview questions.
Understanding JavaScript
JavaScript is a scripting language used in combination with CSS and HTML to create dynamic web pages. Also referred to as the building block of web development, it is used to develop mobile applications, too. The syntax of JavaScript is based on Java and C languages. Here are certain key features of JavaScript.
- Dynamic typing
- Platform independence
- Lightweight
- Control statements
- Line-by-line execution
- Easy interpretation by a web browser
- Functional style
- Prototype-based
- Case sensitive
- Event handling
Understanding ES6
ECMAScript or ES is the standardized specification for scripting languages like JavaScript. JavaScript is an implementation of the ECMAScript specification. ES6, or ECMAScript 6, was the sixth version of the ECMAScript standard released in 2015. It provided certain key contributions to JavaScript, which include:
- Arrow functions
- let and const declarations
- Object entries
- Object and array destructuring
- Template literal
- String and array methods
- for/of loop and others
20 JavaScript MCQs for Front-End Developers
Strengthen your JavaScript basics with JS interview questions and ES6 MCQs:
Q1. State the Characteristics of Negative Infinity.
- It is a constant
- It is variable
- It stated no other number is greater than this value
- Both a and c
Answer: The right answer to this JavaScript MCQ for front-end developers is ‘a’ - It is a constant
Q2. State the Keyword Used to Declare Block-Scoped Variables in ES6.
- ‘block’
- ‘var’
- ‘let’
- ‘const’
Answer: c. ‘let’
Q3. What will be the Output of the Following JavaScript Code?
- Error
- 6
- 2
- 10
Answer: The right answer to this JavaScript MCQ for front-end developers is ‘c’ - 2
Q4. Which of These is Used to Declare a Constant Data Type?
- constant
- cons
- const
- cnst
Answer: c. const
Q5. Which of These is a Class in ES6?
- Function
- Basic data type
- Variable
- Derived datatype
Answer: The right answer to this JavaScript MCQ for front-end developers is ‘a’ - Function
Q6. What is the Role of the JavaScript Engine?
- Compilation
- Interpretation
- Parsing
- Compilation and parsing
Answer: b. Interpretation
Q7. What will be the Output of the Given Code?
- Undefined
- 20
- Error
- 40
Answer: d. 40
Q8. Choose the Correct JavaScript Syntax that can be Used to Modify the Following Statement:
<p id="demo>Welcome to JavaScript Quiz</p>
- Document.get ElementByName(“p”).innerHTML = ”Hello Candidates!”;
- demo.innerHTML= ”Hello Candidates!”;
- document.getElement(“p”).innerHTML = ”Hello Candidates!”;
- document.getElementByID(“demo”).innerHTML = ”Hello Candidates!”;
Answer: d. document.getElementByID(“demo”).innerHTML = ”Hello Candidates!”;
Q9. Where Should You Insert JavaScript Code in an HTML Document?
- The <head>section
- The <body> section
- Both <head> and <body> section
- Anywhere in the HTML file
Answer: The right answer to this JavaScript MCQ for front-end developers is ‘c’ - Both and section
Q10. What is the x = = = y Statement Interpreted as in JavaScript?
- State that x and y have equal value
- State that x and y are not equal
- State that x and y are equal in type, value, and reference address
- State that x and y are equal in value and reference address only
Answer: c. State that x and y are equal in type, value, and reference address
Q11. What is the Purpose of the ‘Symbol’ Data Type Introduced in ES6?
- To represent immutable data
- To define asynchronous operations
- To create unique identifiers
- To create generator functions
Answer: c. To create unique identifiers
Q12. Which Among These is the Correct Combination for Loop on a Loop Variable?
- Initialization, updation, and incrementation
- Initialization, testing, and updation
- Initialization, incrementation, and testing
- Initialization, updation, and initialization
Answer: The right answer to this JavaScript MCQ for front-end developers is ‘b’ - Initialization, testing, and updation
Q13. How can you Determine the Status of a CheckBox Element with the id "IK" in JavaScript?
- document.getElementById("IK").isChecked;
- document.getElementById("IK").isSelected;
- document.getElementById("IK").checked;
- document.getElementById("IK").value;
Answer: c. document.getElementById("IK").checked;
Q14. What is the Primary Difference Between JavaScript and JScript?
- JavaScript is a client-side scripting language, whereas JScript is a server-side scripting language
- JavaScript is developed by Mozilla, whereas JScript is developed by Microsoft
- JavaScript is an open-standard scripting language, whereas JScript is a Microsoft implementation of JavaScript.
- JavaScript is used for creating web applications, whereas JScript is used for creating desktop applications.
Answer: c. JavaScript is an open-standard scripting language, whereas JScript is a Microsoft implementation of JavaScript
Q15. Give the Output for the Following Code:
- 15
- 78
- Runtime error
- Compilation error
Answer: b. 78
Q16. Which is the Use of the Array “map()” Method?
- It only passes the data item of one array to other arrays
- It passes the data item of the array and also returns the essential mapped elements
- It applies a particular function to each element of the array it is called on and generates a new array containing the results of the function calls
- It only maps the elements of other arrays
Answer: c. It applies a particular function to each element of the array it is called on and generates a new array containing the results of the function calls
Q17. Which Function Does Not Return a Value?
- Dynamic function
- Method
- Static function
- Processes
Answer: d. Processes
Q18. Which Function is Used to Eliminate the Last Element From the Array?
- pop()
- deleteLast()
- splice()
- removeLast()
Answer: a. pop()
Q19. What is the Role of Object-Oriented Programming in JavaScript?
- Code organization into classes and objects
- Elimination of the function needs
- Faster code execution
- Shorten the code length
Answer: a. Code organization into classes and objects
Q20. Which is Used to Calculate String Variables in JavaScript?
- let
- const
- var
- All of the above
Answer: The right answer to this JavaScript MCQ for front-end developers is ‘d’ - All of the above
Become a Pro in JavaScript with Interview Kickstart
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FAQs: JavaScript MCQs for Front-End Developers
Q1. How do I Turn on My JavaScript?
To activate JavaScript in the browser, open Chrome, head to settings, privacy and security, and select site setting. Now click JavaScript and select the sites that can use JavaScript.
Q2. Who Introduced JavaScript?
Brendan Eich invented JavaScript in 1995.
Q3. Why Won't My JavaScript Work?
One of the common problems leading to the inability to run JavaScript is corrupted browser cookies or cache.
Q4. Is JavaScript Free and Open Source?
Yes, JavaScript is both free and open source to use.
Q5. Does JavaScript Need a Browser?
JavaScript can run both on web pages and on servers.
Q6. Is JavaScript Used in the Backend?
JavaScript is the common language used for both frontend and backend code.
Related reads:
- Top 20 C Programming MCQs to Test Your Knowledge
- HTML MCQs for Web Development: 22 Must-Know Questions
- Database Management System (DBMS) MCQs for IT Specialists
- Operating System MCQs Every IT Professional Should Ace
- Fundamentals Linux MCQs for System Administrators
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