Front End Developer Interview Questions And Answers

Front End Developer Interview Questions

Front End Developer Interview Questions And Answers for experienced professionals from Codingcompiler. These Front End Developer interview questions were asked in various interviews conducted by top multinational companies across the globe. We hope that these interview questions on Front End Development will help you in cracking your next Front End Developer job interview. All the best and happy learning.

In this blog you’ll learn

Front End Developer Interview Questions
Front End Developer Interview Questions and Answers

Frequently asked Front End Developer Interview Questions
Front End Developer Interview Questions For Experienced

Front End Developer Interview Questions

1. Explain how you would ensure that your web design is user-friendly and what kinds of steps would you use?
2. What are the technical and additional skills that are needed to be a front-end developer?
3. Describe Coffee Script?
4. Explain what is clear?
5. Can you tell us when would you utilize CSS float?
6. Explain what are the difference between Get and Post?

7. Can you tell us when would you utilize CSS clear?
8.  Describe what is a Thread-Local object in Python Flask?

9. Explain the syntax and how to use a Function as A Class?
10. What is Scope in JavaScript?

Front End Developer Interview Questions and Answers

1. Explain how you would ensure that your web design is user-friendly and what kinds of steps would you use?

Answer: A front-end developer needs to talk about working alongside UX(User Experience) designers to imagine and conceptualize a web page that cultivates a user-centric experience, testing the website with users to ensure optimal design and assuring the web page is optimized for mobile phone viewing.


2. What are the technical and additional skills that are needed to be a front-end developer?

A good front-end developer needs to have a working knowledge about:

  • HTML
  • CSS
  • JQuery
  • JavaScript


Apart from the above mentioned technical skills, a front-end developer should have the below mentioned “good-to-have” skills.

  • Experience in any of the Content Management Systems (CMS) like WordPress,  Drupal, and Joomla.
  • Knowledge of cross-browser testing.
  • Knowledge about OOPS and PHP.
  • Basic knowledge about SEO & tools like Dreamweaver and Flash which are utilized to present web-based information to end users.

3. Describe Coffee Script?

Answer: CoffeeScript is a little programming language that compiles into JavaScript. It is an attempt to exhibit the good parts of JavaScript in a simple way. It also assists to write JavaScript code better by presenting you with a more constant syntax and skirting the unusual nature of JavaScript language.


4. Explain what is clear?

Answer: A clear is utilized when you don’t need an element to wrap around another element, such as a float.

5. Can you tell us when would you utilize CSS float?

Answer: 

Float is utilized when you need to make an element of your web page be pushed to the right or left and make other elements cover around it.

6. Explain what are the difference between Get and Post?

Answer: 

A GET request is generally used for things like AJAX calls to an API, whereas a POST request is typically utilized to store data in a database or submit data through a form.

GET requests are limited secure and can be viewed by the user in the URL, whereas POST requests are used in two steps and are not seen by the user. So, POST requests are more secure.


7. Can you tell us when would you utilize CSS clear?

Answer: When I want an element on the left or right of the floating element not to wrap around it, I can utilize clear.


8.  Describe what is a Thread-Local object in Python Flask?

Answer: A thread-local object is an object that is stored in a dedicated structure, attached to the current thread id. Flask utilizes thread local objects internally so that user don’t have to pass objects around from function to function within a request to stay threadsafe.  Besides, Thread local storage performs your logger’s context global but only within the current thread. This approach is helpful, but it needs a valid request context for dependency injection or when attempting to reuse code which utilizes a value pegged to the request.

9. Explain the syntax and how to use a Function as A Class?

Answer:
function functionName(name) {

this.name = name;

}

// Creating an object

var variable_name= new functionName(“Zuan”);

console.log(variable_name.name); //Zuan

10. What is Scope in JavaScript?

Answer: In JavaScript, each function gets its own scope. Scope is basically a collection of variables as well as the rules for how those variables are accessed by name. Only code inside that function can access that function’s scoped variables.

A variable name has to be unique within the same scope. A scope can be nested inside another scope. If one scope is nested inside another, code inside the innermost scope can access variables from either scope.

Frequently asked Front End Developer Interview Questions

11. Explain What Is An Iife?

Answer :

IIFE stands for immediately-invoked function expression; it executes immediately after created by adding a () after the function.

12.  What Is A Callback Function?

Answer :

JavaScript is read line by line. Sometimes, this can result in what seems like a subsequent line of code being executed prior to an earlier line of code. A callback function is used to prevent this from happening, because it is not called until the previous line of code has fully executed.

13.  Do You Know What Is Cors? How Does It Work?

Answer :

Cross-origin resource sharing (CORS) is a mechanism that allows many resources (e.g., fonts, JavaScript, etc.) on a web page to be requested from another domain outside the domain from which the resource originated. It’s a mechanism supported in HTML5 that manages XMLHttpRequest access to a domain different.

CORS adds new HTTP headers that provide access to permitted origin domains. For HTTP methods other than GET (or POST with certain MIME types), the specification mandates that browsers first use an HTTP OPTIONS request header to solicit a list of supported (and available) methods from the server. The actual request can then be submitted. Servers can also notify clients whether “credentials” (including Cookies and HTTP Authentication data) should be sent with requests.

14. Tell Me How Do You Clear A Floated Element?

Answer :

Clear:both

15. Explain What Is An Anonymous Function?

Answer :

Anonymous functions are functions without a name. They are stored in a variable and are automatically invoked (called) using the variable name.

var x = function(a, b) {

console.log(a * b)

}

x(3, 5); // 15

16. What Are This And That Keywords?

Answer :

This and that are important to variable scope in JavaScript. Here are a few stackoverflow posts on this, that and self.

17. How To Clear A Floated Element?

Answer :

A floated element is taken out of the document flow. To clear it you would need to do a clear:both or try overflow:auto on the containing div.

18. How do you structure your CSS and JavaScript to make it easier for other developers to work with?

Answer: Front end developers often work on code created by previous employees or operate as part of a team. This question gives you an idea of whether they can create websites or web applications that will be understandable by other employees. What to look for in an answer:

Experience with code organization and code commenting

First-hand knowledge of what happens when code isn’t commented appropriately

A willingness to make things easier on the other development teams

Example: “I organize my stylesheets with sections for each site component. Each section has comments throughout the code so other developers can change it.”

19. What are your favorite types of front end development projects to work on? What do you like about them?

Answer: This question gives you insight into the personal preferences of the front end developer. Some applicants may prefer to only work on website projects, while others enjoy being involved in web application teams more. What to look for in an answer:

A strong opinion on their favorite types of development
Enthusiasm for the project types they describe
Examples of their favorite front end development projects

Example: “I recently worked on a web application for a local hospital. It streamlined the patient intake process and I loved knowing that my work helped patients get the help they needed faster.”

20. What is CSS preprocessor? Why do we use them?


Answer:

Pre-processor is used for code conversion. The preprocessed languages like SASS and LESS are converted to more formal CSS format. Reasons for using them are

  • Ability to define variables
  • Ability to use nested syntax
  • Ability to create and use mixins (functions)
  • Use of mathematical and operational functions

Front End Developer Interview Questions For Experienced

21. How will you convert non-numerical values to numbers in Javascript?


Answer:

The 3 main ways to do this is –

  • parseInt ()
  • parseFloat ()
  • Number()

22. What is CSS pre-processor? Why do we use them?

Answer:

Pre-processor is used for code conversion. The preprocessed languages like SASS and LESS are converted to more formal CSS format. Reasons for using them are

  • Ability to define variables
  • Ability to use nested syntax
  • Ability to create and use mixins (functions)
  • Use of mathematical and operational functions

23. Do You Know What Is The Importance Of The Html Doctype?

Answer :

DOCTYPE is an instruction to the web browser about what version of the markup language the page is written. Its written before the HTML Tag. Doctype declaration refers to a Document Type Definition (DTD).

24. Explain what is a Closure?

Answer: A closure is a sequence of a function bundled together with references to its enclosing state. It gives you access to an outer function’s scope from an inner function. When a function renders a function, that is when the concept of closures becomes more consistent. The rendered function has access to variables that are not in the global scope, but they individually exist in its closure.

25. What is the difference between null and undefined?

Answer: It can be assigned to a variable and has no value in case of null but on the other hand undefined means a variable has been declared but has not yet been assigned a value.

26. What is the difference between responsive and adaptive web design?

Answer: Responsive Web Design : It built on a fluid grid that will change with the browser automatically, no matter what the screen resolution is holding content can break apart and realign if need be.

Adaptive Web Design : It not necessarily set on a fluid grid; targets specific device resolutions like (320, 768, 1024 etc); can have set relative widths with (%) and controlled by media query.

27. What is front end optimization?

Answer: Front end optimization is also known as content optimization. Basically it is the process of working fine your website to make it quick to load and more browser friendly.

Front end optimization helps in minimizing the number of requests needed for a given page to load and reducing file sizes. CDN plays an important role in the process of front end optimization.

28. What do you mean by Tag In HTML?

Answer: Tags are the hidden keywords within a webpage that define how your web browser display the content. All tags must have two parts just like an opening and a closing part.

For example

opening tag (<div>) and closing tag (</div>).

These symbols (<, >) are also called angle brackets.

29. What is npm?


Answer: NPM stands for Node Package Manager. It is used to install, uninstall, update packages for Javascript Programming Language. NPM also is a default package manager for Node.js.


30. What are css sprites?

Answer: CSS sprites are a combination of multiple images into a single file that we use on our website. CSS sprites help us to load our page faster by reducing the number of file requests.

31. What Is The Difference Between Call And Apply?

Answer :

apply lets you invoke the function with arguments as an array. call requires the parameters to be listed explicitly. Also, check out this stackoverflow answer.

32. Explain Some Common Ie6 Bugs And How You Dealt With Them?

Answer :

Ie6 is not dead, just ask China which represents a nice chunk of the worlds online population. Your pages should at least be functional on IE6, unless you dont care about half the worlds population.

33. Tell Me Are You Familiar With Jasmine Or Qunit?

Answer :

Jasmine and QUnit are JavaScript testing frameworks. I would familiarize yourself with the basics.

34.  What Is The Difference Between A Host Object And A Native Object?

Answer :

Native – existing in JavaScript. Host – existing in the environment.

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