Top 50 Front-End Developer Interview Questions and Answers
Client-side web applications are the responsibility of front-end developers. The user interface is the first thing a user interacts with when they visit a website. For the best user experience, front-end developers make sure that the user interface maintains high functionality and performance in addition to its aesthetic appeal. We will go over a few crucial front-end developer interview questions in this article, which will be very helpful to developers.
- What attributes does a website have that make it user-friendly, and how will you create one?
- Utilizing a simple navigation bar
- using responsive design layout for the best reading experience on mobile
- the incorporation of accessible elements to broaden the website’s appeal to people with disabilities and the elderly
- guaranteeing quicker loading speeds.
- What are some techniques for shortening page load times and accelerating websites?
The methods front-end developers use to increase a website’s functionality and speed are:
- Lighten up large photos for better performance.
- Prefetching or prerendering can be used to load resources in advance of usage.
- What advantages come with using a CDN?
The main advantage of a CDN is that it produces the fastest loading times possible, improving the dependability and functioning of the website. These days, some of the most widely used CDNs are Cloudflare, Microsoft Azure, Google Cloud, Amazon CloudFront, etc.
- How are HTTP methods used and what are they?
Among the most well-liked techniques are:
- GET: Data retrieval is accomplished using GET requests.
- HEAD: accomplishes the same task as the GET method but does not return the response body.
- POST: These requests, known as POSTs, are used to transfer data.
- DELETE: These requests are used to delete certain resources, as indicated by their name.
- OPTIONS: These requests provide data in return and detail the communication channels available for a given resource.
- To make the code more legible, for loops utilize the forEach method.
- The map function is used to alter and make new arrays.
- To reduce an array to a single value, the reduce function removes additional elements from the array.
- With the callback function, the filter function is utilized to construct new arrays.
- The value of the first element in an array that meets a predefined condition is found using the find function.
- What do HTML meta tags do?
The head tag on an HTML page is always where meta tags are located. They are meant for the browser but are not visible on the page. They might include details like the character encoding, the document’s title, description, and other things.
- Describe npm.
Node Package Manager is known by the abbreviation npm. Npm serves two primary purposes. On search.nodejs.org, you may find online repositories for node.js packages and modules. The other is a command-line utility that may be used to install Node.js package dependencies, manage versions, and manage package installations.
- Describe Webpack.
- Callback Hell: What is it?
The asynchronous method requires callbacks as a return parameter. When many asynchronous functions are combined, callback hell happens.
- Describe Sass.
A CSS preprocessor called Sass, or Syntactically Awesome StyleSheets, increases the power and grace of the base language. In addition to other capabilities, it supports variables, nested rules, mixins, and inline imports while preserving a syntax that is fully CSS compatible. Sass makes it possible to quickly deliver small stylesheets while organizing massive stylesheets. By enabling developers to write code in one language and then compile it into CSS, a CSS preprocessor is a scripting language that enhances the functionality of CSS.
- Describe ClickJacking.
An attack known as “ClickJacking” deceives users into believing they are clicking on one thing while they are clicking on another. HTML frames allow for the attack to happen (iframes).
- What does a CSS grid system mean?
A grid system is a framework that enables content to be layered both vertically and horizontally predictably and clearly. Rows and columns are the two essential parts of grid systems.
- Encapsulation: What Is It?
Encapsulation is the process of containing one or more elements inside a physical or logical container. In object-oriented programming, encapsulation is a strategy that limits access to implementation-specific information.
- Cross-Site Scripting (XSS): What is it?
Cross-Site Scripting (XSS) is a sort of attack that takes place when a hacker utilizes an online application to send harmful code to a different end user. This code is often transmitted in the form of a browser-side script.
- Load Balancing: What Is It?
A simple method for distributing workloads over several workstations or clusters is load balancing. The most popular and straightforward load-balancing algorithm is round robin. The circular distribution of requests used in this load-balancing technique makes sure that no machine is overloaded or underloaded and that each one receives an equal number of requests.
16. SQL injection definition
The failure to sufficiently distinguish between user-provided (or external) input and program instructions (i.e., code) leads to injection attacks. This makes it possible for an attacker to insert destructive code into a data sample.SQL injection is one of the most prevalent forms of injection attacks.The attacker injects malicious SQL statements into the software to achieve this.
- Describe Webpack.
- How do you define content security policy?
An HTTP header called the Content Security Policy (CSP) allows site owners to finely manage where the resources for their websites are loaded from. The use of this header is the strongest defense against cross-site scripting (XSS) vulnerabilities. Because it is difficult to retrofit CSP into existing websites, it is mandatory for all new websites and highly suggested for all high-risk websites that already exist.
- Semantic HTML: What is it?
A kind of HTML called semantic HTML aids in defining the significance of tags. As a result, web browsers can read the code more easily. Semantic HTML also helps you save time by automating some of the coding procedures.
- Describe CSS3’s new features.
In essence, CSS is a collection of numerous draughts for forthcoming Standards. New selectors, CSS variables and functions, gradients, opacity, transitions, transformation, animations, flexbox, grid, and media queries are just a few of the new features in CSS3.
- Why is z-index utilized, and what does it mean?
The CSS property known as “z-index” is used to specify the hierarchy of components on the z-axis. It specifies the arrangement of adjacent HTML components. Components with higher index values will be positioned above elements with lower index values.
- What distinguishes let, const, and var from one another?
23. What distinguishes sessionStorage() from localStorage?
A storage mechanism called localStorage is kept in the local storage of the browser. It can be viewed later and throughout several sessions, and it keeps data for the current webpage. An alternate storage method saved in the browser’s session storage is called sessionStorage. It only saves information for the current website session, therefore it won’t be available after closing the browser or during the subsequent session.
- Describe strict mode.
With the help of the new Strict Mode feature in ECMAScript 5, you can put a program or function in a “strict” operating context. This restrictive context raises more exceptions and forbids some actions.
- What do the script> tag’s defer and async characteristics mean?
Deferring execution until after the document has finished parsing is equal to running the script within a DOMContentLoaded event listener. The defer attribute downloads the script while the document is still being parsed. Defer scripts will run in sequence. The async property downloads the script while the page is being parsed, pausing the parser so that it can run the script before it is finished. Async scripts won’t always run in the correct order.
- Explain mixin
A mixin is a piece of code that allows us to organize CSS declarations that we might utilize across our website.
- What does CORS stand for and what problem is it designed to solve?
Cross-Origin Resource Sharing, or CORS, enables requests to be sent from one website to another. However, when requests are sent to other domains by scripts, a browser is not permitted to load those requests for security concerns. By providing a header that specifies which domains are permitted to send XMLHttpRequests, CORS resolves this problem.
- What does “coffee-script” imply?
- What distinguishes null and undefined from one another?
On the other hand, undefined indicates that a variable has been declared but has not yet been given a value. It can be assigned to a variable and has no value if null.
It is a function that wasn’t assigned a function named identifier when it was declared. Following its first establishment, it is typically not accessible. At runtime, these functions are produced.
- Domain pre-fetching: what is it?
Before a user clicks on a link, the IP address of the website is resolved through a process called domain prefetching.
- What accomplishes JSON.stringify()?
- What purpose does clear serve in CSS?
It is a CSS property that is employed to specify that floating elements are not permitted. “none” is its default value. Additional choices include “clear: left” and “clear: right.”
- What does the KISS principle mean?
The U.S. Navy created the design tenet KISS, an acronym for “keep things simple, stupid,” in 1960. According to the KISS principle, systems perform best when kept simple rather than convoluted. Because of this, design should always be kept straightforward and avoid adding extra complexity.
- What distinguishes “resetting” and “normalizing” CSS from one another? Which one should you choose, and why?
Resetting is intended to erase all of the built-in styles on elements in the browser. Fonts, padding, and margins are all reset to zero. Normalizing maintains the useful styles rather than discarding them all. Additionally, it can correct every problem for common browser requirements. Resetting is preferable if you’re working on a truly unique website design and need to add a lot of your flair.
- Describe the prototyping design pattern.
New things are produced by the prototype pattern. However, the oddity is that it returns objects that are initialized with values copied from a prototype – or sample – object, rather than creating non-initialized instances.
A function that is defined inside another function and has access to a variable is referred to as a closure. The parent function scope is where this variable is both declared and defined.
- Why do we need the W3C Standard Code?
Cross-platform interoperability and smaller file sizes are two of these standards’ primary objectives. By utilizing CSS, these standards seek to separate “content” from “formatting.” It makes development and maintenance easier.
- What is the purpose of DOCTYPE?
The acronym DOCTYPE, which stands for Document Type, is connected to the DTD (Document Type Definition). Developers can then tell the browser which version of HTML is being used in a given document.
- What do you mean when you say “lazy loading”?
Lazy loading is one technique for adjusting content loading on the browser to the user’s requirements. The utilization of servers and resources is optimized as a result.eCommerce platforms like Flipkart and Amazon provide a practical illustration of this.
- How does the server interact with websites or programs that provide material in many languages?
The user’s browser sends information about the user’s preferred language when they access these websites. Using the Accept-Language header, this is accomplished. The language is sent back in the appropriate language by the server after reading this data and using it.
- What does HTML’s data-* attribute means, and is its use now recommended?
Custom information that is specific to a web page is stored using the Data-* property. Using this, the web site’s developers can fix bugs or make secret adjustments. The use of data-* attributes is discouraged because the inspect console in the browser can now accomplish the same task.
The “does” keyword has a similar notion to dynamic binding, which is used in other high-level programming languages. It is used to make references to the thing it is connected to.
- How well-versed are you in progressive rendering?
Progressive Rendering is a technique for speeding up the process of rendering content on any webpage. This helps the user use their mobile data as efficiently as possible. Async HTML, prioritizing visible content, lazy loading, and other ideas are all part of progressive rendering.
47. Why is the’srcset’ element used in the img> tag?
The’srcset’ attribute is used to render the same image in multiple resolutions depending on the browser or device being used. The purpose of this is to enhance user experience and guarantee that they view the image in the highest resolution possible for the device they are viewing it on. We can make sure that the browser shows high-quality photos on devices and browsers with good resolution and low-resolution images on other devices by using srcset.
48. How would you guarantee the usability of your website or application?
The front-end developers must collaborate with UX (User Experience) designers to conceptualize web pages that answer the concerns of the audience it is intended for to guarantee that the website or web application is user-friendly. The objective is to develop a user-centered experience that works well on many browsers and screens and has the best design flow, content, and page structure.
- What do HTML “templating languages” mean?
A placeholder language called “template language” enables users to enter data into any HTML document. Back-end frameworks deal with a variety of templating languages.
- What should be preferred—external JS/CSS or inline JS/CSS, and why?
The size of the page is increased by inline coding, which slows down code execution. The user browser is no longer able to cache and store CSS and JS code for quicker execution when inline coding is used. However, the browser can cache external CSS and JS files, which speeds up page load times.
Top 50 Front-End Developer Interview Questions and Answers: FAQs
- What is included in front-end development?
- What opportunities are there in India for front-end developers?
Since front-end developers create websites and applications that represent an organization to the outside world, there is always a demand for their services.
- What are some of a front-end developer’s everyday responsibilities?
The responsibilities of front-end developers include transforming static designs from the graphic design team into dynamic, useful web pages.
- Can front-end engineers transition to full-stack development later on?
Definitely. As you work more frequently with back-end engineers and gain expertise as a front-end developer, you will gradually begin to understand full-stack principles as well.
- In front-end development, who can find employment?
Anyone with an aptitude for design and an interest in web development can learn the skills necessary to launch and flourish in a career in web development.