6 December, 2019
Front-End Developer Interview Questions

Top 50 Front End Developer Interview Questions and Answers in 2019

Front end web development requires a strong knowledge of all languages. And the interview questions always could go past beyond our expectations. Hence, you need to cover all web technologies such as HTML/CSS/JavaScript/AngularJS/Node.js.

Top Front End Developer Interview Questions and Answers.

The following list of front end developer interview questions and answers is helpful to you can use to prepare the interview for the front end developer.

1. What makes up a good Front-End Developer? What are his responsibilities?
  • Empathy – Empathy means being able to understand and share the perspectives and experiences of someone else
  • Problem-Solving – Problem-solving is not solving personal problems. It is about coding fixes. A good developer should be able to fix code.
  • Critical Thinking – Being able to solve problems with new approaches and technologies.
  • Googling – Being able to craft a search term that gets to the root of what you want to do.
2. What are the technical and additional skills that are needed to be a front-end developer?

A front-end developer should have working knowledge on HTML, CSS, Jquery,and javascript. Additionally, the front-end developer should have knowledge on content management tools (Any one), cross-browser testing, and basic SEO tools.

3. What is a callback function?

A callback function is a function passed into another function as an argument, which is then invoked inside the outer function to complete some kind of routine or action.

4. Can you tell us when would you utilize CSS float

CSS Floats are used when we develop a page that resizes dynamically based on user’s resolution.

5.Can you describe your workflow when you create a web page?

Each developer will have different kind of workflow based on organizational capacity and technical preferences. And, there are many tools available on the web for organizing web pages.

6. Can you explain what Three.js is and quote its key features?

Three.js is a cross-browser JavaScript library and Application Programming Interface and used to create animated 3D computer graphics in the browser. The key feature of three.js is that it can display the graphics without use of extensive plug-ins.

7. What’s your process for addressing browser-specific rendering problems? Do you find that a certain browser is more challenging to work with than others?

There are multiple ways to address browser-specific rendering. The simple way is to use a conditional statement in the head tag of your HTML. In this way, you can recognize the browser and load an external stylesheet.
No. I don’t.

8. Explain what is the difference between Class and Prototypal inheritance?

This would be a tricky question asked by interviewer. A class is a description of the object created. A prototypal inheritance is a working object instance.

9.What are your favorite features of HTML5, and how have you implemented them in your front end development projects?

HTML5 handles multimedia support. I use this feature to develop a design to incorporates videos and audio as an essential part of the experience without worrying about it not loading properly or breaking the page.

10.What is CoffeeScript? What are the Ways in which CoffeeScript is Superior to JavaScript?

Coffeescript is a little programming language that compiles into a Javascript. To make it simple, we can write code in Coffeescript and run it in compiler and display the output in javascript.

11. What resources do you use to learn about the latest in front end development and design?
  • Best Resource for learning Front End development and Design
  • CodeAcademy
  • TreeHouse Blog
  • Echo JS
12. How do you ensure that your website design or web application is accessible and user-friendly?

A front-end developer should imagine a web page which gives a user-centric experience, and test the website with users to ensure optimal design and assuring the web page is optimized for mobile phone viewing.

13.Explain what are the difference between Get and Post?
    • Get method passes request parameter in URL string whereas post method passes body content of the request parameter.
    • Get request can pass limited data whereas post request can accept unlimited data.
    • Get request can be bookmarked but post request can’t be.
14.What Are The New Features Introduced In HTML5?
      • Editing Content within Elements
      • New Structural Elements
      • Accessibility and Responsiveness
      • Allows to embed audio and video on web pages
      • Persistent Local Storage
15.Can you briefly explain what a Thread-Local object in Python Flask is?

A thread-local object is an object that is stored in a dedicated structure, 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.

16. Explain the difference between classes and IDs?/h6>

IDs are used to style elements that occur only once in a web page, whereas classes are utilized for different web elements but in the same fashion.

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

Cors is a mechanism that allows restricted resources on a web page to be requested from another domain outside the domain from which the first resource was served.

18.Explain Why Table-less Layout Is Very Important?

Table-less layout is a method used to avoid the use of HTML tables for page layout control. Instead, it uses CSS are used to arrange elements and text on a web page.
It improves the accessibility of the information
Saves Bandwidth
Maintainability

19.How To Optimize The Page Using Front End Code Or Technology?
  • Proper placement of CSS Style sheets and Java attributes
  • Reduce external HTTP requests
  • Minimize the use of CSS, JS and HTML
  • Optimize the Images
  • Use Minimal Frameworks
  • Use Browser cache side with cache control
20.What is Event Bubbling?

In event bubbling, event starts from child nodes or target nodes to its source node or parent node.

21.Explain how do you deal with browser-specific style incompatibility?

Conditional statement should be utilized in the head tag of HTML

22.Can you describe your workflow when you create a web page?

While designing any web page i will follow this flow.

  • Planning
  • Wireframe Outline
  • Design
  • Code
  • Test & Debug
  • Launch

Also Learn More about Best Way to Learn Angular 7 from Scratch in 2019

23.What is the importance of the HTML DOCTYPE?

DOCTYPE is an instruction to the browser regarding what version of the markup language the page is being written. It points to DTD and should be declared before the HTML tag. DOCTYPE provides the rules for markup so that the browser can interpret the content correctly.

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

Host objects are objects supplied by the environment itself and they will not be same always whereas native object are built-in objects and it will be same always.Hence, native objects are referred as Global objects.

25.Tell Me Why Do We Recommend External Css Or Javascript Versus Inline?
  • External CSS is easy to maintain and everything will be stored in single file.
  • If we updated any changes, the changes are reflected on all other pages that reference the stylesheet.
  • Easy to maintain larger websites.
  • Using External CSS makes pages load quicker
  • Entire look and feel of a website can be changed through a single file.
26.What is the difference between XHTML and HTML?

HTML syntax is SGML-based whereas XHTML is xml-based.

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

function functionName(name) {
this.name = name;
}
// Creating an object
var variable_name= new functionName(“Talent”);
console.log(variable_name.name); //Talent

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

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

29.Explain the difference between visibility:hidden; and display:none?
  • Visibility:hidden – It is not visible but it gets original space
  • Display:none – It is hidden and doesn’t have any space.
30. Explain how variables differ in CoffeeScript than JavaScript?

In JavaScript, variables should end with a semi-colon for execution. However, with CoffeeScript, there is no necessity to add a semicolon at the end of every statement.

31.Can you explain the functions in CoffeeScript?

The syntax of function in CoffeeScript is simpler as compared to JavaScript. In CoffeeScript, we define only function expressions.
The function keyword is eliminated in CoffeeScript. To define a function here, we have to use a thin arrow (->).
The CoffeeScript compiler grabs the body of the function that we have separated using indentations and placed within the curly braces.

32.Can you list the differences between WebGL and Three.js?

WebGL: is the Javascript API which is used to create 3D graphics in the browser.
Three.js: A framework build on top of WebGL which makes it easier to create 3D graphics in the browser, it uses a canvas + WebGL to display the 3D scene.

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

clear:both

34.Explain What Is An Anonymous Function?

Anonymous functions are the functions without name. These functions are stored in a variable and can be invoked using the variable name.
var x = function(a, b) {
console.log(a * b)
}
x(3, 5); // 15

35.What Are This And That Keywords?

This and that are important to variable scope in JavaScript.

36.Tell Us The Purpose Of Each Of The Http Request Types When Used With A Restful Web Service?
  • GET: Retrieves data from the server
  • POST: Sends data to the server for a new entity.
  • PUT: Replaces an existing entity.
  • PATCH: Update only certain fields within an existing entity.
  • DELETE: Removes data from the server.
  • TRACE: Provides a means to test what a machine along the network path receives when a request is made. As such, it simply returns what was sent.
  • OPTIONS: Allows a client to request information about the request methods supported by a service.
  • HEAD: Returns the response headers (i.e., with no entity-body).
  • CONNECT: Primarily used to establish a network connection to a resource
37.Have You Ever Used A Css Preprocessor/precompiler? What Are The Benefits?
  • Nested syntax
  • Variables can be defined
  • Mixins can be defined
  • Mathematical functions
  • Operational functions (such as “lighten” and “darken”)
  • Joining of multiple files
38.Explain What Is Web A Application?

It is an application utilizing web and web browser technologies to complete one or more tasks over a network, typically through a [web] browser.

39.Explain what is a Closure?

A closure is an inner function which has the access to variables of outer function.

40.Explain the difference between cookies, session storage, and local storage?

Cookies allow the pages to store data in the browser.
Session storage allows applications to store data till the window is closed.
Local storage property saves the application without an end.

41.What is lazy loading?

Lazy loading is a design pattern commonly used in computer programming to defer initialization of an object until the point at which it is needed. It is a loading code used whenever the user needs it.

42.What are the applications of clone-function in CoffeeScript?
  • Copy all attributes of source object
  • Creation of object similar to the source object
43.Can you briefly explain what a Thread-Local object in Python Flask is?

A thread-local object is used to store the object in a dedicated structure, and is attached to the current thread id. Flask utilizes thread local objects internally so that user has no need to pass objects for each and every function within a request to stay threadsafe.

44.Explain what is Event Delegation?

Event delegation refers to the process of using event propagation (bubbling) to handle events at a higher level in the DOM than the element on which the event originated.
It avoids the use of adding event listeners for specific nodes every time. Instead, you can add a single event listener to a parent element.

45.What Is Variable Scope?

A variable can be either of global or local scope. A global variable is a variable declared in the main body of the source code, outside all functions, while a local variable is one declared within the body of a function or a block.

46.Explain what is the difference between Class and Prototypal inheritance?

Prototype-based inheritance allows us to create new objects with a single operator; Whereas class-based inheritance allows us to create new objects through instantiation.

47. Have you ever used an MVC? Which one and what do you like and dislike about it?

MVC is model-view-controller. It is an architectural design for implementing UI on computers. This question by interviewee is tricky. Interviewees should be expressive why they use MVC over other designs.

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

I will use clear when I want the element to be in left or right of the floating element not to wrap around it.

49. Describe what is the difference between Null and Undefined?

Null can be assigned to any variable with no value. Undefined means variable can be declared but not assigned with value.

50.Explain What Is Ajax? Write An Ajax Call?

Asynchronous javascript and XML (Ajax) is for creating faster, scalable and more interactive application with javascripts. With Ajax, request and response is possible in fraction of seconds without reloading the web page. Example: Gmail Inbox.
Simple Ajax call for request
$.ajax(‘/jquery/getdata’, // request url { success: function (data, status, xhr) {// success callback function $(‘p’).append(data); } });

Conclusion :

Preparing for interviews isn’t as easy as it seems to be. If you are aspiring to get a job, then You should have a basic idea of related areas.
To sum up all the functionalities, we have given front end web developer interview questions covering web technologies like HTML5, CSS3, and JavaScript. We have covered almost all topics. If we have missed out any important questions, please leave your queries in the comment section.

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2 Comments

  1. Vimal Reply

    i am am web designer, searching for front end development interview questions. this post is very helpful to me attending interviews, thanks for updating this and keep it and add more questions & answers.

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