Front-End Development Interview Questions

October 6,2020 - 10 min read
 Front end development interview questions

A website or an application is built by the efforts of a number of developers, designers, engineers and thinkers. One such set of people who are responsible for engaging the user with visual, interactive elements on the website are called the front-end web developers. They are also called as the client-side developers as they create an experience for the clients (the end-user). On the other hand, backend development is called the server-side development.

The web designers decide upon the look and feel of the website and frontend Developers actually implement them on the web.

Every organisation, big or small, is looking for skilled front-end Developers who can build an excellent user interface and attract more users to its website.

Today, we are going to discuss some of the most important front-end developer interview questions. Front end development consists within itself an array of technologies and the stack is continuously growing. From basic HTML and CSS to advanced libraries and frameworks like React and others. In this blog, we have compiled some of the basic questions for frontend Developers. We hope you get an insight and these questions help you become a front-end developer in your dream company. Let's get started.

Q1) What is HTML and CSS?

This is a very general question and would probably find its place in the beginning of the interview. Most of you would know its answer but here is a concise definition of HTML and CSS.

A1) HTML stands for Hyper Text Mark-up Language. It is a standard mark-up language for web pages. CSS stands for Cascading Style Sheet. It is a style sheet used for describing the presentation of a document written in a mark-up language.

CSS defines the style of an HTML webpage. It describes the behaviour, position and style of all HTML elements. CSS is also responsible for the layout of the webpage.

Q2) How do we link CSS in a HTML document?

A2) There are mainly three ways to link a CSS file to the HTML document. The first way to link CSS is inline style. It is the simplest method to add styling. The inline style is applied using the style tag to a particular element in the HTML document itself. The syntax for the same is –

<p style=” colour: #000FF”>

The second way to add styling is Embedded. In this way, you can add a number of CSS styles in a single HTML document. It is also described using the style tag.

The third and the most popular way to add CSS styling is by adding the External style sheet. In this, the user has to make a separate CSS file and save it with a .css extension. The syntax for linking the external stylesheet to the HTML document is –

<link rel=” stylesheet” type=”text/css” href=“style.css” />
Q3) What is Doctype and why do we declare it?

A3) All HTML documents have to start with a <!DOCTYPE>. It is a kind of declaration however it is important to note that <!DOCTYPE> is not an HTML tag. The ‘doctype’ tells the browser what type of document to expect.

Q4) What is the Meta Tag in HTML?

A4) Meta tags, as the name suggests, contain the information about the document. The kind of information the meta tag contains is the likes of character encoding, description, the title of the document etc. The meta tags always go inside the <head> tag of the HTML document. It begins with the meta tag. The information enclosed under the meta tag is intended for the browser and is not displayed on the webpage.

Q5) What is the difference between HTML tags and elements?

A5) Tags are a basic formatting tool in HTML and other mark-up languages. Elements are one of the components of the HTML document. HTML tags are used to hold HTML elements and HTML elements hold the content.

The five questions above were very basic and are generally asked at a beginner’s level. In short, they were easy ones. Now we move on to an advanced set of questions.

Q6) When do we use CSS float?

A6) Float is one of the most important properties in CSS. It has two values and they are left or right. Float is used when you want to adjust an element to the right or left and the inline elements to wrap around it.

Q7) What are frames in HTML?

A7) Frameset is basically a tag in HTML. It is used to create several frames in the single web page and each of those frames can contain separate HTML documents. The tag is used to divide the browser window into several frames.

In most of the professional websites, the navigation bar is another frame containing a separate HTML document and the rest of the web page is a different frame containing another HTML document. For a detailed analysis of frames in HTML, you can refer to this blog.

Q8) What are margins in CSS?

A8) Margins refer to the space that exists outside of the borders. In CSS they refer to the exact same thing. Margins are used to create spacing around the HTML elements. CSS gives you the freedom to decide how much margin you want to keep at all four sides (top, bottom, left and right) of an element.

Margins can push or pull to create space between the element and the browser window or between two elements depending on the configuration of the web page. For a detailed analysis of margins in CSS, you can refer to this blog.

Q9) What is bootstrap?

A9) Bootstrap is an open-source CSS framework. It contains CSS and Javascript based design templates for applying advanced styling to the layout and different elements of the HTML document. Bootstrap is a popular responsive front-end framework that is used to build modern websites and applications.

Q10) Explain the importance of Javascript in front end web development.

A10) JavaScript is an object-oriented language used for creating interactive web pages. Javascript is an event-driven, functional and imperative language.

It is popularly used to make dynamic effects on web pages like rollover, rollout and other interesting functionalities. Javascript is very important in the field of web development as it is used by over 94% of all websites as a client-side language.

Q11) What is React?

A11) Reactjs, essentially a javascript library. It is used to build fast and interactive user interfaces for web and mobile applications. One of the most attractive features of React is that it is open-source, developers can easily access the source code and modify it according to their application.

React is easier to learn as compared to other frameworks and there are a number of recent developments in React like the latest extension which can be used to cross-compatible make mobile applications.

Q12) What is the difference between React Native and React?

A12) React is a Javascript library that is used to build the UI interface as a front-end web and is being run on the server. React Native is a mobile framework that allows us to create native mobile applications i.e iOS, Android and windows.

Q13) What is webpack and why do we use it?

A13) Webpack is an open-source Javascript module bundler. It is basically a build tool that puts all of your assets in a dependency graph. These assets may include Javascript images, fonts and CSS. Webpack is usually used with a complex application which has non-code static assets.

Q14) What is the grid system in CSS?

A14) The grid system in CSS allows the contents to be placed vertically and horizontally in a consistent manner. The grid system makes it easier to build webpages without having to use floats and position. The two key components of a grid system are rows and columns.

Q15) What is a virtual DOM? Explain in the context of React.

A15) DOM stands for document object model. A virtual DOM is a lightweight object of Javascript. The virtual DOM is a node tree made out of React components. The function render () is used to create the tree.

Virtual DOM is that it allows mutations whenever there are changes made by the user or the system. In the occurrence of a change, the entire UI is rendered in the virtual DOM and then the virtual and the real DOM is compared. Only the differences are updated in the real DOM and not every change.

Q16) What are the advantages of virtual DOM?

A16) A virtual DOM updates the JSX elements faster and manipulation is easier and quicker than Real DOM. Another advantage of virtual DOM is that there is no memory wastage.

Q17) What is the difference between websites and web applications?

A17) Website is a collection of interlinked pages like Homepage, Information page and others which have a single domain name. On the other hand, a web application is a software program that is accessed on the internet.

Sometimes it is seen that a web application is implemented as a part of the website or a website is implemented as a part of the web application.

Q18) What is the box model in CSS?

A18) Box model is used in CSS to specify the design and layout of any HTML web page.

The box model treats every HTML element like a box. The box has certain properties that define the styling and design of the element. The box that wraps every element consists of the content, margin, border and padding.

Q19) What is the difference between padding and margins in CSS?

A19) Padding and margin in the CSS box model look very similar to each other but in reality, their functionalities are totally different. In short, there are three different properties of the box models in CSS.

Padding is used to create space within an element whereas margins, as we discussed, is used to create space between elements. Margin refers to the gap between adjacent elements while padding refers to the space between the content of the element and the element itself.

Q20) How will you ensure that the website you build is user-friendly?

A20) Apart from good technical knowledge, a front-end developer should coordinate well with graphic designers and UX/UI developers. Good communication skills are a must in order to execute the role of a successful front-end developer. The website should be responsive and adaptable to various screen sizes.

We have tried to cover some important front-end development interview questions. However, if you feel there are any questions or concepts of front-end development interview questions that we omitted or if you have any doubts regarding the topics discussed above, please feel free to ask questions and we would be more than happy to answer.

This blog was a comprehensive compilation of some possible questions that can be asked in a frontend a interview question. We hope you now have a clear understanding of the interview questions that will be asked if you apply for the position of a frontend developer. If you really want to become a successful front-end developer then apart from the theoretical knowledge, you should also undergo professional training.

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