Front end Developer Interview Questions and answers 2022

Front-end web development has become one of the IT industry’s most high demand domains and job roles today. It is one of the most high-paying domains with great scope for growth and earning. The fundamental skills required in this role are knowledge of  CSS, HTML, JavaScript and the working of servers. This makes front-end development a valuable step toward a full-stack development career. The front-end development domain in itself is also quite comprehensive as it covers a wide range of tools and techniques. To understand a candidate’s grasp on each of these concepts, front-end developer interview questions are diverse and cover several domains.

In today’s technology-driven world, programmers must have a high level of proficiency in coding to help them convert the requirements of a client into a finished product. In front-end developer interviews, the hiring professional is always looking for this high proficiency level in candidates who take initiative. The leading IT organisations of the world want to hire developers who can lead app building and management projects and create solutions that are responsive and interactive. This must be done keeping in mind the needs and convenience of the client.

If you are just starting in the front-end development and programming domain and don’t know how to prepare for your interview, you’re in the right place. Understanding the different types of interview questions that you are likely to face can significantly improve your chances of answering them correctly and getting your dream job as a front-end developer. Take a look at the following questions based on specific domains that you will most likely face in your next interview. 

What is Front-end Development?

Front-end app development encompasses everything within the web development domain that focuses on what end-consumers and end-users see on their screens. It aims at modifying the code that backend developers create and transform it into an effective and usable graphical interface while ensuring that all necessary data is provided in a manner and format that makes it easy to comprehend. WIthout front-end development and programming, end-users would only see a page full of indecipherable code every time they opened a web application or website. Everything you see on a website, including this article, social media platforms and search engines, is a result of front-end developers working closely with backend developers to bring you the desired experience. 

Front-end developers have a wide range of duties and responsibilities besides ensuring users understand the GUI of the application. They must customise the app screen for different devices and operating systems and also build solutions that can function on every web browser platform across devices including Google Chrome, Firefox, Microsoft Edge, Opera and Safari.

To understand the level of skill development you need to answer all front-end interview questions, take a look at the most common interview questions asked below.

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Front-End Interview Questions By Domain:

GIT Interview Questions-

Q1. What is VCS?

VCS is short for a version control system, a program used to record any changes made to a data set of a file so that it can be restored to any previous version whenever necessary. A VCS ensures that all the members of a team work on the latest file version at all times. 

Q2. What are the differences between a Centralised VCS and a Distributed VCS?

The following are features of a Centralised VCS:

  • All the versions of a file get stored on a centralised server.
  • No single developer or professional has an entire copy of files on a local system.
  • All project data will be lost permanently if the central server of the project fails.

The following are features of a Distributed VCS:

  • All developers have copies of all the code versions on their individual systems.
  • A Distributed VCS can improve user capabilities to work offline and negates the need for a central data backup location. 
  • If a single server crashes, all the data is not permanently lost. 

Q3. What do you know about Git Push and Git Pull?

Git Push is a Git command that moves all the contents in a local data repository to a remote one. The Push command runs after it changes its local repository so that the remote team can access these new changes.

Git Pull is a specialised Git command that takes file changes from one remote repository and merges these changes into a local data repository. There are two commands in Git Pull - git fetch and git merge, applied in the same order. 

Q4. Name some of the leading Git functions and commands.

Some of the most widely-used Git functions are: 

  • Git Config - Configures username and email
  • Git init - Initialises local Git repositories
  • Git Add - Adds at least one to the staging area
  • Git Diff - Opens the changes made to the file
  • Git Commit - Commits changes to the head but not to the remote repository
  • Git reset - Undoes local changes made to a Git repository
  • Git Status - Displays the state of the working directory and staging area
  • Git Merge - Merges a new branch into an active branch
  • Git Push - Uploads content from a local repository into a remote repository
  • Git Pull - Fetches and downloads content from a remote repository to a local system

Q5.  What is the difference between Git Pull and Git Fetch?

Git Fetch only downloads new data from a remote repository. None of this information is included in any local working files. Developers run Git Fetch whenever they try to update their remote-tracking branches.

On the other hand, Git Pull helps draw new data and integrate it with existing working files. It also updates the present HEAD branch with any new modifications made to the remote server. Git Pull aims to combine remote changes with local changes to create a single updated document. 

HTML Interview Questions

Q1. What is an HTML attribute?

An attribute is a property that developers can add to a regular HTML tag and change the way it behaves or appears. Developers add attributes after an HTML tag’s name, within the brackets but immediately after.

Q2. What is Marquee in HTML?

Marquee helps developers and users scroll through the text on a webpage. Marquee is used for scrolling an image up, down, right or left automatically. The tag <marquee> tag is used to apply for a marquee.

Q3. What is Semantic HTML and how does it work?

Semantic HTML refers to a method of coding where HTML markup is used to emphasise the meaning or semantics of the existing content. 

Q4. How do you display a table on an HTML webpage?

There are several tables used to define different parts of a table. These are as follows:

  • <table> defines the table.
  • <tr> defines one of the rows of the table.
  • <th> defines the header cell of a table.
  • <td> defines a cell in the existing table.
  • <caption> defines the caption of the table.
  • <colgroup> specifies a group of several columns within a table that needs to be formatted. 
  • <col> is used together with <colgroup> to specify the properties of every column.
  • <tbody> is useful while grouping a table’s body content.
  • <thead> is useful in grouping a table’s header content.
  • <tfooter> groups the content of a table’s footer. 

Q5. What is SVG in the context of HTML?

HTML SVG is a markup programming language used to describe raster and vector graphics. XML text files are a defining component of SVG pictures and any associated behaviours. Generally, SVG is used for diagrams with an X-Y coordinate system such as 2D graphs or pie charts. 

Q6. How can you separate one section of text in HTML?

The following tags can help developers to divide one part of a large body of text. 

  • The <br> tag is a character that breaks up one line of predefined text. It breaks an existing text line and transfers the flow of the text to a new one.
  • The <p> tag helps create a paragraph of text. 
  • The <blockquote> tag indicates large quoted passages or sections of text. 

Q7. What is the difference between an ordered list and an unordered list?

Ordered lists use the tags <ol> and </ol>. Every element on the list is generally written between the <li> and </li> tags. 

Unordered lists use the <ul> and </ul> tags. Every element on this list is written between the <li> and </li> tags.

ALSO READ: How to Become a Front-End Developer - A Step by Step 2022 Guide?

CSS Interview Questions:

Q1. What is the most effective way to include CSS styling within HTML?

To incorporate CSS stylings in HTML, three methods can be used.

  1. Inline CSS is useful when styling is required for just a single element or when only a little styling quantity is required. 
  2. An external style sheet is used when a CSS style is applied to several HTML pages or elements.
  3. An internal style sheet comes in handy when an HTML document is made of several elements and has a unique style. 

Q2. What do you know about the Box Sizing property?

The Box Sizing property in CSS defines how developers should calculate the width and height of a box. 

Content Box is when the default height and width get applied to the content of an element. The border and padding lie outside the box.

Padding Box is when the developer adds the dimensions to include the padding and content of the element. This adds a border outside the given box.

Border Box is when the box dimensions apply to the border, padding and content. 

Q3. Define the ways in which you can hide an element using CSS.

There are three ways to hide elements with CSS.

  1. <display:none> can hide the content so that it doesn’t get stored in the DOM.
  2. <visibility:hidden> adds an element to the DOM and occupies space. However, the user cannot see it.
  3. <position:absolute> makes the element appear outside the screen, not on the screen. 

Q4. Define CSS Sprites.

Every image sends a separate HTTP request. This means a web page with more photos will take more time to load. A CSS Sprite minimised a web page’s loading time by blending several small pictures into one big picture. 

JavaScript Interview Questions:

Q1. What are the different types of data in JavaScript?

There are several data types in JavaScript that are essential for the basic functioning of web applications. They are:

  • Boolean - true or false values
  • Null - empty or unknown values
  • Undefined - variables that aren’t initialised or defined, only declared
  • String - alphanumeric values and characters
  • Number - floating-point and integer values
  • Object - Complex values or collections
  • Symbols - unique objects or identifiers

Q2. What does Callback mean in JavaScript?

Callback is a JavaScript function that developers send as a parameter or argument to other functions. You can call this function whenever the function it is provided to gets called.

Q3. State the differences between Function Declaration and Expression.

Function declaration is written as

function abc(){

    return 5;

}

In the main code in JavaScript, the function declaration is a separate statement. Developers can invoke it before the function is defined as it helps improve the readability of the code.

Function expression is written as

var a = function abc(){

    return

}

Function Expression is created within a construct like an expression. Its primary use is when you need a conditional declaration for a function.

Q4. What do you know about JavaScript Cookies?

A cookie refers to a small byte-sized piece of information or data that a website sends and which gets saved on a user’s computer system by the browser they are using to access this page. Cookies help systems and browsers remember data to use later and track the browsing activities on the website. The easiest way to make a cookie using JavaScript is:

document.cookie = "key1 = value1; key2 = value2; expires = date";

To delete cookies, developers simply set an expiry time and data. Spelling out the right path of any cookie is a good JavaScript practice. This can be done this way:

function delete_cookie(name) {

      document.cookie = name + "=; Path=/; Expires=Thu, 01 Jan 1970 00:00:01 GMT;";

    }

Q5. What are Closures in JavaScript?

In JavaScript, a Closure is a feature through which inner functions can access the variables of the outer function. Closures have three chains of scope.

  • It can access the variable defined within its curly braces, known as its scope.
  • It can access the variables of the outer function(s).
  • It can access global variables.

Q6. What do you know about imports and exports in JavaScript?

Export refers to files that export two functions designed to calculate the diagonal and squares of the respective input. 

Import refers to files that import these same functions and pass the input to the functions so that the diagonal and squares can be calculated. 

Q7. Explain the differences between Undefined, Undeclared and Null in JavaScript.

Undefined refers to a situation where a variable is declared but no value has been assigned to the variable yet.

Null refers to the assignment of value to a variable that isn’t meant to contain any value.

Undeclared refers to variables that don’t exist in an application or program or haven’t been declared. 

Q8. What is the most effective way to delete duplicates from an array in JavaScript?

There are two ways to remove duplicates from a given JavaScript array:

  1. You can employ the filtering technique. Here you need three arguments to call a filter() function. These arguments are the current element, array and current element index.
  2. You can use the For loop and store every duplicate element in an empty array.

ReactJS Interview Questions

Q1. What is JSX?

JSX is a syntactic extension in JavaScript and a term that describes what a user interface should look like. Using JSX allows developers to write JavaScript code and HTML structures within the same file. It also makes code easy to debug and understand by avoiding complex JS DOM structures. 

Q2. What is Virtual DOM?

Virtual DOM is a lite version of Real DOM that gets retained in memory by React. While processing Real DOM, there is nothing drawn on the screen. For this reason, handling Virtual DOM is much faster in comparison.

Q3. What do you know about React extensions? Can you give a few examples?

React is not just a user interface framework. It is made up of several diverse extensions that encompass entire application architectures. It also allows server-side rendering and supports mobile app development. Redux and Flux are two popularly known extensions, among others. The application architecture Facebook uses to develop online apps is Flux. Additionally, developers can create entire mobile apps from scratch in JavaScript using React Native.

While these front-end interview questions are fairly comprehensive and cover all the fundamentals, they are not the only questions you can face. However, they show you the domains you should focus on, the skills you should develop and how you should frame your answers. There are several instances that recruiters recount where even good candidates fail to get the job just because they don’t know how to frame their answers. You can also choose to get mentored by experts and industry veterans before your interview and enrol in a training course on Koenig today. Give your career the boost it deserves and register now. 

Armin Vans
Sheyans is a Android Certified Developer and certified professional with rich experience in Application Development, Programming, and Corporate training. He delivered training on CEH, CPENT, ECSA, Security+, CNDV2, CISSP, CISM, Android, iOS, Java, Objective C, Swift, and Xamarin Mobile Framework.

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