Talk to me about z-index and how stacking context is formed.

"Z-index is a CSS property that determines the z-order of an element position within the container and its descendants. Elements with larger z-index cover or overlap those with smaller ones. This is also known as stacking context. Stacking context allows an element with a fixed position to overlap one with a large z-index, especially if the z-index value is auto."

An interesting question that may be difficult for inexperienced front-end developers to answer. It appears to be two separate questions and can be answered as such. However, the two topics addressed in this question are related. You can respond to this question by addressing this relationship. How you respond to a question like this is not as important as demonstrating your knowledge of the topic and providing the information the interviewer is looking for.

Are you familiar with the term CoffeeScript, and do you know how it is used in front end web development?

"CoffeeScript is just another version of JavaScript. It is actually a sub-language that compiles code into JavaScript. The benefit of CoffeeScript is that it uses more natural language and less code, and therefore is easier for new programmers to use. Its ease of use and minimal coding requirements has made CoffeeScript very popular since its release in 2009. Other programming languages similar to CoffeeScript include Python and Ruby."

One of the benefits of Java is that it is open-source, and anybody can develop code that is Java compatible. This has resulted in a wide array of java libraries, sub-languages, and related techniques. No matter how experienced you are as a front-end developer, it is virtually impossible to know about all of these. As with any question, if you're familiar with the concept, answer the interviewer's question. If not, let them know how you would locate the information and offer to provide them an answer after the interview.

What does the acronym CORS stand for, and what programming issue does it help resolve?

"CORS is an acronym which stands for Cross-Origin Resource Sharing. You can use CORS to make requests from one website to another one. CORS addresses a browser not being allowed to load requests to other domains when scripts generate those requests. This is prevented for security reasons. By supplying a header that will define which domains can make appropriate requests, CORS is a good work-around for this limitation."

When interviewing for a front-end developer role, you will be asked many different technical questions about a wide variety of technologies used when designing websites. While it is impossible to know about every one, you should be familiar with the major topics and discuss them in some detail. If, for some reason, you aren't familiar with the topic raised by the interviewer, quickly admit this and then describe how you would go about locating the information.

Please discuss the differences between the call, apply and bind commands?

"Call, apply, and bind are commands that pass arguments within a web program. The difference between them is how they pass the arguments. Call invokes a function with a given value and passes arguments one by one. Apply does the same thing; however, it passes the arguments as an array. Blind first returns a new function, which is then passed in an array which can contain any number of arguments."

Regardless of the language you program in, many different commands and functions control the actions on the website. The user interface and the programs control these. You don't need to memorize all the commands and functions used in your programs, but you should know the major ones and how they differ. This enables you to select the appropriate command for the actions you want the site to perform. More obscure commands can be looked up in programming manuals if needed.

Can you provide men an overview of the Delegation Event Model?

"The Delegation Event model is a technique website developers use to handle events in Graphical User Interface or GUI-based programming languages. The model provides developers was standard and consistent mechanisms to generate and process events. One of the benefits of using a delegation event model is that the events it processes are separated from the user interface logic that generates the events. This provides the developer more flexibility and of flying both of GUI and the related events."

Front-end developers use as many standards and models as possible when designing websites. This simplifies the designs and ensures that the website will be compatible with the browsers, platforms, and operating systems users will employ to access it. This is why front-end developers work in languages such as Java which has large libraries of programs and code that can be used repurposed in their designs. You can expect a lot of questions about the standards and models you use.

Our web development team uses JSONP. Are you familiar with this, and do you use it in your web development?

"I am very familiar with JSONP and use it frequently when developing front ends for websites. The P stands for processing, so JSONP is a Javascript technique that allows you to parse, generate, transform and query JSON messages from a remote server. When returning a Javascript function to a remote server, the function needs to be evaluated, which requires a Javascript function such as JSONP. JSONP works very well with jQuery."

During the interview, the interviewer is likely to ask about technologies their team currently uses. You want to make sure you are familiar with these and can easily adapt to the processes and procedures the organization currently employs. Before the interview, you should research the job and the company to understand the technologies they use. Sources for your research can include the job description, the company website, and talking with both current and former employees of their development team. Once you know the technologies they use, you can either become familiar with them, refresh your understanding, or be prepared to acknowledge that you are not familiar with them and suggest an alternative.

Can you discuss the differences between session storage, cookies, and local storage?

"The three types of storage mechanisms I use when developing a website front end are session storage, cookies, and local storage. Session storage is the data that is stored only while the website is open. Once the user closes the website, anything which was stored in session storage is deleted. Session storage is minimal, can only be read on the client-side, and increases as the user opens multiple windows on the site. Cookies reside on the user's devices and store information that is sent back to the server each time the user accesses it. Cookies are stored on user devices but only read by the server. They are dynamic and can be updated each time the user connects with the server. Finally, the last type of storage is local storage. The data is stored on a client computer, which shares the data with a web browser. This type of storage is kept until deleted by the user. Web sites access local storage using JavaScript and HTM5."

There are three main types of storage used by websites. Each of these has unique characteristics and benefits. Knowing about these and employing them in your designs will demonstrate your qualifications as a front-end developer. When describing each type of storage, its characteristics, and the differences between them, keep your answers brief and to the point. The interviewer will ask a follow-up question if they need additional information.

What is Representational State Transfer, or REST, and how would you use it when developing a front end for a website?

"REST stands for Representational State Transfer. It is a software architectural style that guides the designs of a website and defines a set of standards to create web services or APIs. Some of the items addressed by REST include the scalability of the site, how the components of the website interact with each other, creating uniform interfaces, deploying the components of the website independently, and caching components to reduce their latency. Another benefit of using REST is that it enforces strict security measures and can encapsulate legacy systems."

As a front-end developer, you likely use several different technologies to create your websites. However, you may not use every single technique the interviewer will ask you about. If you're familiar with the technique, answer the interviewer's question as best you can. If not, readily admit this, and then describe to the interviewer how you would locate information about the technology and possibly incorporate it into your work.

Please describe what the acronym NPM stands for and how it is used in front end development.

"NPM stands for Node Package Manager. Front-end developers use it to install, uninstall, and update packages for Javascript Programming Language. NPM also is the default package manager used for Node.js."

Within every technology-related profession, hundreds if not thousands of acronyms are used. Using acronyms facilitates communication as long as both people understand the meaning of the acronym. During an interview, you will be asked about many different acronyms, what they stand for, and their usage. You should be able to address all of these questions easily. However, you should avoid using acronyms when responding to an interviewer's questions. Never assume that the interviewer understands an acronym or any other technical term.

"Node package manager. it allows you to install and update packages for your project. You install modules like React, Jest, Lodash, etc."

Can you describe Ajax and discuss what it is used for?

"Ajax, which stands for Asynchronous Javascript and XML, is a methodology used to create asynchronous web applications. The benefit of using Ajax is that applications developed this way can send and retrieve data asynchronously. The benefit of this is that it doesn't interfere with the existing page of the application because transmission of the data occurs in the background. Ajax is a combination of several technologies, including XML, HTMML, CSS, DOM, JSON, and JavaScript."

Any qualified front-end developer should be able to describe a wide variety of technologies used in their profession. Interviewers will ask you about these throughout an interview. The best way to respond to these types of questions is to briefly describe what the interviewer is asking about, discuss how it is used to develop websites, and possibly provide an example to illustrate your answer.

Which technique do you prefer to use, resetting or normalizing CSS, and why?

"Resetting and normalizing CSS both address how individual browsers render and style the code. Resetting CSS removes all built-in browser styling. This results in individual elements relative to each type of browser styling the content and the same way. Normalizing CSS seeks to standardize built-in browser styling across all the browsers. While the results are the same, I prefer normalizing CSS to ensure a consistent user experience."

This is an example of a hybrid technical and operational question. It asks you about a technical concept used in a front-end developer's work and then asks you for your preference. This will require you to define the concepts, state which one you prefer, and then justify your choice. Following this format will walk the interviewer through your answer in a logical fashion. Hence, they will clearly understand your expertise in this area and why you prefer the technique you described.

How would you integrate several different stylesheets into a website?

"When I develop a web page, I try to minimize the number of stylesheets I use. This is because they are transparent to the users, and they impact performance. However, if I use multiple style sheets, I integrate them by concatenating them into a single sheet. The best way I've found to do this is by using Gulp and initiating npm to track the dependencies between the individual style sheets."

As you're probably aware, a style sheet defines how the pages will appear within a website. Since style sheets have a great deal of overhead and require individual HTTP requests, developers often seek to minimize the number that they use. While one is ideal, many developers prefer two; one for the front end and one for the site's administrative side. Even so, you should be able to describe how you integrate several style sheets, assuming that this is the current practice the organization you are interviewing with uses.

Can you compare progressive enhancement and graceful degradation?

"Progressive enhancement and graceful degradation are two methodologies used to move users from older technologies to newer ones. Progressive enhancement begins by providing basic functionality to users employing the old technology, increasing the functionality for users who adopt the new technologies. Graceful degradation works in reverse. This provides full functionality for users of the new technologies and gradually degrades users' functionality who are still on older platforms or technologies. The basis behind this is to encourage users to adopt new technologies such as advanced web browsers."

This is an example of a technical question. Technical questions ask you about concepts, processes, or procedures used in your profession. This particular question asks you to compare two of these. When responding to a technical question, you should first define each concept and discuss its differences or similarities. Keep your answers brief and to the point, and anticipate a follow-up question.

What are floats, and how they work?

"Floats are a property that positions an element within its container and then allows text and other elements to wrap around it. Floats remove the element from the normal flow of the page. Elements with absolute positioning remain fixed and will not wrap around a float. An alternative to floats that will create the same effect is display: inline-block."

This technical question asks you to define a concept used by front-end developers and describe its function within a website design. As an experienced front-end developer, you should easily be able to answer this question. Throughout the interview, the interviewer will ask you questions of this nature. They may switch from easy questions like this to more complex ones. Anticipate this inconsistent questioning methodology. Continue to answer technical questions briefly and directly, and be prepared for a follow-up question, which indicates the interviewer has a specific interest in the topic they are asking about.

Describe what CSS selector specificity is and how it works?

"A CSS selector is used to find the HTML elements you want to style. When using a CSS selector, specificity occurs if two or more CSS rules point to the same element. The browser will select the rule that is more specific in defining the HTML element. This is based on a score created by the CSS selector."

This technical question asks you about a specific topic within the purview of a front-end developer's job. Many of the questions you will be asked during an interview will be technical. To prepare for these, you should review the terminology, processes, and concepts used in this profession to be familiar with them. You can also practice questions like this so you'll know how to format your answers. As with any question, you should be prepared for a follow-up if the interviewer wants to explore the topic in more detail.

What methodologies do you use to ensure that your web application is user-friendly?

"Once I decide on a website's basic structure, I turn my attention to how the users will navigate it. I design elements that make it easy to find your way around my site and locate the information you are searching for. I also access the site using various web browsers to determine what the user experience will be."

One of the key elements front-end developers need to include in their web designs is the ease of use. It doesn't matter what content the website contains or how robustly it performs if users can't easily access and navigate it. Incorporating ease of use and user-friendliness in your design will encourage the users to explore the site and take advantage of its features.

"I design the user interface with simplicity in mind for the user. The easier it is for the user to navigate through the application the accomplish their goal, the more they are willing to further engage with the application for their needs. Examples of this include creating visible and contrasting elements on the page for better visibility and simpler navigation."

Walk me through your workflow when you are creating a web page.

"While every project is different, the process I use to develop a web page is relatively consistent. I start by collaborating with the website designer in the information gathering, planning, and design phase. Once we've completed this, we begin writing and assembling the content. The next step is coding, in which the structure and functionality of the website are developed. This was followed by testing, user reviews, and launch. The website then transitions to the maintenance phase in which content is updated, bugs are fixed, and security issues are patched."

An interviewer will ask you this question to better understand your process to create a web page. They want to ensure that you have a definitive process for doing this and that it aligns with the processes they use within their organization. This is an example of an operational question. During an interview for a front-end developer's job, you can anticipate that most of the questions will be operational. The best way to prepare for these is to review the processes used in your work, the job description, and your resume. This will help you anticipate the questions that will be asked and be prepared to respond to them.

Can you define Block Formatting Context and describe how it works?

"Block formatting context is a part of a visual CSS rendering of the elements within a web page. Visual formatting describes how user agents use the document tree and display it for visual media. The block formatting context defines the region which contains the layout of block boxes and defines how floats interact with other elements within the region. The root element of the document creates it."

You should immediately recognize this as a technical question. You are first asked to define a concept used in the front-end developer profession and then describe how it works. This is the classic form of a technical question. Make sure your answer is brief and to the point, and anticipate a follow-up question. This will indicate that the interviewer has a particular interest in this topic and may want to explore it in more depth.

What version control systems have you worked with?

"During my career as a front-end developer, I have worked with many version control systems. These all fall into one of the three main categories, which include local, centralized, and distributed systems. The only difference between these three is how and where they are managed. The software I use for version control includes both open source, such as RCS, OpenCVS, and SCCS, and some proprietary systems. These include AccuRev, various IBM products, PTC, Razor, and Vault, to name a few."

One of the key principles of developing code for any application is version control. This ensures that any changes made to the code are documented and that the developers can revert to older versions of the newly developed code that does not function properly. Being familiar with and utilizing version control systems is a fundamental requirement for any front-end developer. You can anticipate that you will be asked this question in virtually every interview.

Can you explain the techniques you use to ensure front-end security?

"As a front-end developer, security is one of my key concerns, second only to the performance of the website. By incorporating security practices in the code's original development, I eliminate the need to constantly fix leaks or combat hacks. My first step in this process is to use a framework that handles security automatically. Examples of this include View, Angular, and React. I've also begun incorporating Trusted Types into my development. This is a new browser API from Google which addresses XSS issues. Finally, I compartmentalize the individual applications rather than deploying them as a single piece of code. This makes them harder to hack and minimizes the damage when there are penetrated."

The purpose of front-end security on a website is twofold. The first is to keep the client and their data secure. The second is to prevent the client from accessing parts of the website that they shouldn't reach. Companies will be interested in how you perform this task since it protects both their users and the company from data loss, hacking, and liability issues. Since this is an operational question, be sure to keep your answer direct and to the point.

How has working with the 'this' keyword changed in JavaScript ES6?

"Fundamentally, working with the 'this' keyword in JavaScript ES6 hasn't changed that much at all. What has changed are the rules for scoping and how specific the variables are. These changes were made to correct the vagueness around which 'this' references. By adding specificity and additional variables, 'this' is now easier to work with and requires less debugging."

As a front-end developer, you are expected to keep up with changes in your profession and stay current with the technologies you use. Being able to describe and discuss these is a key element of any interview. You may also want to formulate opinions as to whether these changes are beneficial and be able to describe how they impact the work you do.

When working on a web development project, what do you do to improve your code's maintainability?

"Since I've been working in this role for several years, I've encountered situations in which I've been asked to work with code which has been developed by someone else. This has taught me to incorporate maintainability into my development process. Techniques I use include iterative development, such as Agile or Waterfall, making my code readable, and documenting everything. Other techniques include single responsibility, the law of Demeter, and the open/closed principle. I have never been contacted by a developer who assumed responsibility for my code to ask me to help them understand it."

When interviewing for a front-end developer position, you can anticipate that the interviewer will ask this common question. There is a high turnover rate for developer roles because they are recruited to other organizations or promoted within the same organization. Therefore, other developers must read, patch, and improve the code if the original developer is unavailable. Hiring managers will seek to confirm that you incorporate maintainability into your development process and that the techniques you use are similar to the ones their organization employs.

"I would break it down into 3 categories:Maintainability:- Small components, don't make the code take up more than 100 lines- Folder structure that makes sense.- Avoid duplicate code, make generic functions to be reused- Avoid generic variable names but also shouldn't be overly long- Documentation: comment on things that aren't self-explained by the code and let semantic code take care of the rest- Style guide: have a general UI/UX style guide and theming within styled componentsScalability:- Modular components are components that have a single purpose and do that purpose very well and are agnostic to how it's used in the application. But also don't over modularize so that you have too many files interacting with each other- Choose less opinionated software so you're flexible in how you use it. Like angular is more opinionated, you have to use its built-in router and API fetcher whereas in react you can choose your own and swap them out based on your needs or updates in the web worldPerformance:- Avoid re-renders- Small bundle size- Small npm libraries- Prefetching like for pagination- Lazy loading like for images."

Can you explain how prototypal inheritance works?

"Prototypal inheritance is one of the forms of inheritance used within JavaScript. It differs from classical inheritance by supporting the cloning of any object and using object linking. JavaScript uses prototypal inheritance to read a property from an object if the property is missing. It also allows any function to be added to an object in the form of a property."

While this technical question doesn't specifically ask you to define the term prototypal inheritance, you should start your answer by doing this. This ensures that you are responding to the right question and providing the information the interviewer is requesting. Once you define the term, you can then move on to describing how it works. Sometimes, during an interview, you may want to clarify or confirm a question before providing an answer. This is especially helpful during very technical interviews in which the terminology could have several different meanings.

Tell me about the SEO best practices or techniques you use in your work.

"When seeking to optimize the SEO for a website I am developing, I collaborate with a website designer so we are both on the same page as to what content and code will contribute to this objective. Some of the techniques I can utilize include using digital PR to earn backlinks, improving my organic CTR using PPC testing, using internal links to supercharge the rankings, optimizing core web vials, and optimizing the site for image search."

While SEO, or search engine optimization, is the primary responsibility of the website designer, as a front-end developer, you also need to contribute to how easily the website is located by search engines. Knowing the various techniques and incorporating them into your code will help optimize SEO and drive traffic to the site.

Please discuss the difference between null, undefined or undeclared variables.

"Null, undefined, and undeclared are different types and states of variables used within the JavaScript programming language. Null is a value of a variable, which is a type of object. A variable is considered undefined when declared, but no value has been assigned to it. An undeclared variable occurs when the code tries to access the variable, and it has not been initialized or declared earlier using a var or const keyword."

Another technical question asking you to discuss the differences between several terms or concepts used in this profession. To prepare for an interview, you should research the company, the products it produces, and the type of programming you're likely to encounter. You can find information about this on the company's website and in the job description. Once you understand this, you should be prepared to answer questions related to the work they do. Any answer you provide to a question should be within the context of this.

"Null is an actual value that's an object that you can assign to a variable.Undefined means no value has been assigned to a variable but it has been declared.Undeclared means the name of the variable hasn't even been defined yet using let, var, or const. The first two will result in a false check-in of statements and the last will give a runtime error."

How do you go about addressing browser-specific rendering challenges?

"Developing web pages that are rendered correctly by various browsers is one of the greatest challenges in this job. While Chrome and Firefox are easy to work with, Microsoft Edge often poses problems. I pay special attention to the CSS, ensuring that it is either inline, embedded, or external so that the CSSOM Tree is constructed appropriately. If done correctly, both of the DOM Tree and the Render-Tree are constructed by the browser so that the webpage displays as it is intended to."

One of the challenges front-end developers must overcome is that users employ several different browsers when accessing web pages. Each of these browsers renders the webpage differently. Therefore, code must be written so that it adapts to each browser and renders the page correctly. Knowing the answer to this question demonstrates your ability to accomplish this and your familiarity with the various web browsers.

"Firefox, Chrome, and Safari are easy to account for. However, internet explorer and edge are a bit harder. You can use an automatic polyfill to make things work on older browsers. Also, styled-components automatically add prefixes so styles with other browsers like firefox like adding in the Moz- prefix"

What features of HTML5 have you implemented in your front end development projects?

"One of the key features of HTML5 which I've implemented in projects I worked on include its robust support of multimedia, and the ability to embed both video and audio seamlessly. I also take advantage of the vast libraries associated with the language, its built-in debugging features, and the ability to code in natural language."

Since front-end developers use HTML5 quite a bit, you should be able to talk extensively on this topic. When preparing for an interview, you should research the company, the software it develops, and the projects you anticipate working on. You can find this information on their website and within the job description. This will allow you to frame your answer within the context of the job they are seeking to fill and the tasks they expect you to perform.

How do you use a closure when you are writing front end code?

"A closure is a JavaScript function that can access an outer function scope's variables and functions even after the function has finished. It can be used to implement encapsulation, iterators, and singleton in JavaScript. The closure also enables callbacks, event handlers, and higher-order functions to access outer variables. Finally, a closure will allow you to write functions that can capture data from a site at a specific moment in time."

While the use of closure within JavaScript seems straightforward, it can be confusing. Being able to describe how it is used accurately will differentiate you from many other front-end developers. This is a question you are likely to be asked later in the interview due to its complexity. It will indicate that the interviewer is gaining confidence in your ability and is interested in exploring your qualifications in more detail. Even though it's late in the interview, continue to provide answers directly to the point.

How do you increase the performance of a new web site you develop?

"There are several techniques you can employ to optimize the performance of a website. These include enabling compression, reducing redirects, leveraging browser caching, optimizing images, and eliminating render-blocking JavaScript. Of these, caching is probably the most effective."

This is an example of an operational question. Operational questions help the interviewer understand the techniques and processes you use to accomplish your work. When responding to an operational question, keep your answer brief and to the point. Anticipate that the interviewer will ask a follow-up question to explore the topic in more detail.

Please discuss CSS float and give me an example of how you use it when developing web sites.

"A CSS float instructs the browser to place an element in a specific position within the container. This is a useful tool because it allows me to develop web pages that resize dynamically depending on the user's browser's resolution. The alternative uses fixed-position elements, which may not be properly rendered if the browser resolution is different from what I have designed for."

This is an example of a technical question. When interviewing for a front-end developer's role, most of the questions you will be asked will be technical. Technical questions usually ask you to define a term, concept, process, or operation used in this job. You then will be asked to describe how it is used, compare it to another similar term, or give an example. When answering this question, first define the term or concept and then respond to the interviewer's specific question.

"A float makes elements flush to the left or right. when floats it "rises" above non floated elements and non floated elements go behind the floated elements. Floating multiple to the left will make them all on one line but clearing an element will make it go to the next line."

Front End Developer Interview Questions

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1. Talk to me about z-index and how stacking context is formed.
2. Are you familiar with the term CoffeeScript, and do you know how it is used in front end web development?
3. What does the acronym CORS stand for, and what programming issue does it help resolve?
4. Please discuss the differences between the call, apply and bind commands?
5. Can you provide men an overview of the Delegation Event Model?
6. Our web development team uses JSONP. Are you familiar with this, and do you use it in your web development?
7. Can you discuss the differences between session storage, cookies, and local storage?
8. What is Representational State Transfer, or REST, and how would you use it when developing a front end for a website?
9. Please describe what the acronym NPM stands for and how it is used in front end development.
10. Can you describe Ajax and discuss what it is used for?
11. Which technique do you prefer to use, resetting or normalizing CSS, and why?
12. How would you integrate several different stylesheets into a website?
13. Can you compare progressive enhancement and graceful degradation?
14. What are floats, and how they work?
15. Describe what CSS selector specificity is and how it works?
16. What methodologies do you use to ensure that your web application is user-friendly?
17. Walk me through your workflow when you are creating a web page.
18. Can you define Block Formatting Context and describe how it works?
19. What version control systems have you worked with?
20. Can you explain the techniques you use to ensure front-end security?
21. How has working with the 'this' keyword changed in JavaScript ES6?
22. When working on a web development project, what do you do to improve your code's maintainability?
23. Can you explain how prototypal inheritance works?
24. Tell me about the SEO best practices or techniques you use in your work.
25. Please discuss the difference between null, undefined or undeclared variables.
26. How do you go about addressing browser-specific rendering challenges?
27. What features of HTML5 have you implemented in your front end development projects?
28. How do you use a closure when you are writing front end code?
29. How do you increase the performance of a new web site you develop?
30. Please discuss CSS float and give me an example of how you use it when developing web sites.

Front End Developer Interview Questions

1. Talk to me about z-index and how stacking context is formed.

2. Are you familiar with the term CoffeeScript, and do you know how it is used in front end web development?

3. What does the acronym CORS stand for, and what programming issue does it help resolve?

4. Please discuss the differences between the call, apply and bind commands?

5. Can you provide men an overview of the Delegation Event Model?

6. Our web development team uses JSONP. Are you familiar with this, and do you use it in your web development?

7. Can you discuss the differences between session storage, cookies, and local storage?

8. What is Representational State Transfer, or REST, and how would you use it when developing a front end for a website?

9. Please describe what the acronym NPM stands for and how it is used in front end development.

10. Can you describe Ajax and discuss what it is used for?

11. Which technique do you prefer to use, resetting or normalizing CSS, and why?

12. How would you integrate several different stylesheets into a website?

13. Can you compare progressive enhancement and graceful degradation?

14. What are floats, and how they work?

15. Describe what CSS selector specificity is and how it works?

16. What methodologies do you use to ensure that your web application is user-friendly?

17. Walk me through your workflow when you are creating a web page.

18. Can you define Block Formatting Context and describe how it works?

19. What version control systems have you worked with?

20. Can you explain the techniques you use to ensure front-end security?

21. How has working with the 'this' keyword changed in JavaScript ES6?

22. When working on a web development project, what do you do to improve your code's maintainability?

23. Can you explain how prototypal inheritance works?

24. Tell me about the SEO best practices or techniques you use in your work.

25. Please discuss the difference between null, undefined or undeclared variables.

26. How do you go about addressing browser-specific rendering challenges?

27. What features of HTML5 have you implemented in your front end development projects?

28. How do you use a closure when you are writing front end code?

29. How do you increase the performance of a new web site you develop?

30. Please discuss CSS float and give me an example of how you use it when developing web sites.