Web Developer Interview Questions

You are looking for web developer interview questions since you want to hire competent web developers. Hiring the right web developer can take plenty of effort since they are in great demand. 

The global web development market – already large – is growing significantly. Knowledgeable observers expect that this market will grow from $60.7096 billion in 2022 to $96.7484 billion by 2028. They estimate a healthy 8.08% CAGR during the 2023-2028 period. 

Naturally, technology giants want to shape this market in line with their strategies. They have invested heavily in web development technologies. Therefore, you have a variety of web development technologies and tools, e.g.:

• Google’s tools and technologies for developing web applications;
• Microsoft web application development technologies and tools like ASP.NET.

Varied programming languages, web frameworks, and tools make the landscape of web technologies vast, making it harder to hire good web developers. A comprehensive set of web development interview questions can help, which is what we offer. 

Junior Web Developer Interview Questions

Interview junior web developers using the following questions:

1. State the outcome of the 2 highlighted lines of JavaScript code and explain the reasons.

Code Example:

“

var x = 3;

var y = 4;

var z = 3;

(x == y) // What will this line of code return?

(x == z) // What will this line of code return?

“

Answer:

The first line will return a value of “false”, and the second line will return a value of “true”. By using the “Boolean” data type of JavaScript, the above lines of code are evaluating the following, respectively:

• Is the variable x equal to the variable y?
• Is the variable x equal to the variable z?

Since the variable x isn’t the same as the variable y, the first line returns “false”. The second line returns “true” since x is the same as z.

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2. Which JavaScript libraries can you use for changing the structure, content, and style of the “Document Object Model” (DOM)?

Web developers can use jQuery, a very important software development tool to change the style, content, and structure of the document object model. We can also use Umbrella JS. These JavaScript libraries make DOM manipulation easy.

3. How to validate HTML elements in a Node.js web app?

Web developers can use “W3C HTML Validator”, which stands for “World Wide Web Consortium Hypertext Markup Language Validator”, for validating HTML documents. It’s a Node JS package that you can install using NPM (Node Package Manager). W3C HTML validator creates detailed results after validating HTML files. 

4. Tell me an easy way to develop RESTful web services in a Java web application.

We can use JAX-RS. It’s a comprehensive API method for developing RESTful web services in Java web apps and web pages. We can easily use JAX-RS since it’s an API and a typical web server already implements it.

5. How will you prevent a “Cross-Site Request Forgery” (CSRF) attack in a Ruby on Rails web application?

Interactive web applications and web pages developed using Ruby on Rails can prevent CSRF attacks using an effective web security measure. We need to add the option “protect from forgery” into the Ruby on Rails ApplicationController. Our Ruby on Rails web application will now require a CSRF token to execute requests. When we create forms using the Ruby on Rails form builder, those forms already have the provision of a CSRF token in the form of a hidden field.   

6. At a high level, explain how you can tune the performance of a web application written in Golang.

We can use the following high-level approaches to optimize a Golang web app: 

• We can reuse existing objects, alternatively, we can use buffers for memory allocation. By doing these, we can avoid unnecessary memory allocation.
• We should use synchronization effectively, furthermore, we should use channels and Goroutines smartly.
• Golang developers can simply the programming logic for loops so that the number of iterations reduces. 
• We should use efficient algorithms for programming.
• Golang programmers should proactively identify performance issues by using the profiling tools built into the language.

7. I want to rapidly develop a fast web app. Should I use Django?

Django is a powerful web framework based on Python, an advanced one among coding languages. Django will be a good choice for your project for many reasons. Since you want to quickly develop a fast web app, the following two advantages of Django are particularly relevant to you:

• The MTV architecture of Django makes for a faster transmission of web content. This architecture also makes the use of a content delivery network (CDN) easier, therefore your app will deliver web content faster. 
• Django uses web components that are loosely coupled, partly due to its MTV architecture. This facilitates rapid development.

8. Mention the newly introduced input types that are introduced with HTML5 forms.

The newly introduced input types that are introduced with HTML5 forms are as follows: 

• “date”;
• “datetime”;
• “datetime-local”;
• “month”;
• “time”;
• “week”;
• “color”;
• “email”;
• “tel”;
• “search”;
• “range”;
• “number”;
• “url”. 

Intermediate Web Development Professional Interview Questions

Use the following web developer interview questions to assess mid-level web developers:

1.  Suggest one easy way to achieve responsive web design in an Angular app.

We have several ways to create a responsive user interface for an Angular app, and using Angular Material is one of the easiest options. Angular Material is a CSS (Cascading Style Sheets) library. 

The Angular Material library provides us with a responsive grid system. Web development professionals can easily organize layouts of Angular web apps. 

They can use the 12-column layout of Angular Material. By using this layout, they can position the content in the desired location accurately and quickly. Angular Material enables developers to adjust their apps automatically to different devices and web browsers.   

2. Describe how to re-render views in React apps at the time of resizing web browsers.

We need to take the following steps to re-render views in a React app when the user’s browser is resized:

• We should use the event listener in “componentDidMount()” method.
• The event listener will help us to detect that web browsers are resized.
• We should remove the event listener from the “componentWillUnmount()” method.
• Subsequently, we should modify the height and width dimensions.
• We should render the view again.

3. Should I keep the Express JS web app and server setups together? Provide reasons for your recommendation.

Separating the Express JS web app and web server will be a smarter web developer job, due to the following reasons:

• You get more flexibility when you maintain the codebase separately from the web server.
• Developers can easily define middleware, routes, and other components in the Express app. They can do this independently without worrying about the web server configuration. You get better modularity.
• Programmers can test middleware, routes, and several other components without starting a web server. Unit testing becomes easier.
• Your configuration management tasks become easier if you maintain the Express JS web app and server separately.
• Keeping the app separate from the server helps you to maintain the code when the app becomes bigger. 
• Separating the Express JS app from the server promotes reusability. Developers can use the same app with various configurations of web servers.

4. At a high level, describe the different HTTP requests supported by Node JS.

Node JS developers can use the following HTTP requests:

• “GET”: Apps use this HTTP request method to retrieve the data they need.
• “POST”: Programmers use this HTTP request method to modify reactions on a server or change a state.
• “DELETE”: Web developers can use this HTTP method to delete a resource specifically identified.
• “HEAD”: The HTTP method called “HEAD” acts like the “GET” method, however, it only gets the part of the response excluding the body of the response.

5. How can I import SVG files in my JavaScript web app? What are the pros and cons of the options available to me?

You can import Scalable Vector Graphics (SVG) files in various ways into your JavaScript web app and JavaScript files. These are as follows:

1. A) You can use the HTML “img” element. 

This easy method creates a hyperlink for the SVG image. The page load time is reduced due to the caching of SVG files. 

However, this method doesn’t allow you to manipulate the SVG file. You can only use CSS inline elements to style the SVG and not the CSS pseudo-classes.

    2. B) You can include the SVG file in an HTML document.

You can use the HTML tag named “<object>” for this. Yet another easy method, this approach allows you to use internal or external CSS styles to style the SVG. You can take advantage of browser caching too.

A constraint involving external CSS and JavaScript files exists though. If you plan to use an external CSS style, then you must make use of a “<style>” element within the SVG file.

    3. C) You can embed an SVG file by using an “<iframe>” tag.

This is yet another method of importing SVG files in a JavaScript web app by using HTML tags. You can use “<iframe>” tag for this. While this is an easy and fast option, you can’t use JavaScript functions to manipulate SVG files. Also, this approach doesn’t provide for good browser caching.

6. Should I use generics on my Java web development project?

You should proactively consider using generics on a Java web development project. You get the following advantages:

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• Your code will indicate the types clearly.
• Type-checking improves by using generics.
• Generics in your code reduce down-casting from class objects. 
• Coding work reduces if you use generics, which increases efficiency.
• Maintenance becomes easier since code is easier to read.

While some programmers might feel that using Java generics is more complex, competent Java developers won’t have this challenge.

7. Since I can’t use Java applets anymore on my web development project, suggest an alternative.

You shouldn’t try to use Java applets since you will face browser compatibility issues. Java applets were useful for creating interactive web content, however, JavaScript is now a well-established programming language for developing interactive web applications. Use JavaScript since all the different web browsers support it.

8. For my Python-based web app, I need to store a few small but important strings locally. Suggest an easy approach.

To store data locally for your Python web app, you can use the “localStoragePy” API. Among well-known web platform APIs, “localStoragePy” makes local storage easy to implement. You can install it easily using PyPi and “pip”, the Python package installer. Python developers can use simple commands to store data locally using this API.

9. Demonstrate an easy way to convert a variable with decimal points in Golang into an integer.

There are many capabilities in Golang to convert a variable with decimal points into an integer. Web developers can directly cast a decimal point variable into an integer, which is a very easy approach. Let’s assume that we have a variable named “decimalvar” with a value of 24.23. The following code will directly cast into an integer:

“

package main

import “fmt”

func main()  {

    var decimalvar float64 = 24.23

    var integervar int = int(decimalvar)

    fmt.Println(integervar)

}

“

10. In a Ruby on Rails web app, there was a vehicle with ID=”537”. We deleted it. Show an ActiveRecord query that will raise an error when we search with that vehicle ID. Also, show an ActiveRecord query that will not show any error if we search with the same vehicle ID.

The following query will create an error:

“

vehicle.find(537)

“

This ActiveRecord query will attempt to find the vehicle with ID=”537”, however, it can’t find that.

On the other hand, the following query will not create any error:

“

vehicle.find_by_id(537)

“

This second ActiveRecord query will return “nil” but not show any error.

11. List the elements that support media content in HTML5.

The elements that support media content in HTML5 are as follows:

• Audio: You should use it for embedding audio content into web pages. 
• Video: Use it for embedding video into a web page.
• Source: One should use it for mentioning the source of media content. 
• Track: You need to use it for creating captions and subtitles for audio or video content.
• Embed: Use this element for embedding multimedia content like Flash animations.

Senior Web Developer Interview Questions

Evaluate the coding skills of senior web developers using the following questions:

1. Explain what the following code example is about.

Code example:

“

div  {

   width: 320px;

   border: 18px solid blue;

   padding: 52px;

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   margin: 21px;

}

“

Answer:

This is an example of the CSS box model. The code above creates a box to wrap around web elements like HTML elements. The code starts with the “div” tag, then it proceeds to specify the width of the content. Subsequently, the code specifies the padding, border, and margin.

2. I want to develop a website using JavaScript or a JavaScript-based web framework. The website should rank high on Google searches. It should offer quick loading of web pages, and it should be optimized for social media. I don’t mind higher software development and infrastructure costs for this. The speed for interactive actions isn’t a priority for my website. Suggest an approach.

You should use Server-Side Rendering (SSR). SSR improves the SEO ranking of JavaScript-based websites. It also optimizes JavaScript-based websites for social media queries. SSR enables faster page-loading for JavaScript-based websites.

Since SSR is more complex, the software development effort and cost could go up. The IT infrastructure costs can also go up since the rendering of the JavaScript content takes place on your own servers. The user interaction time could go up due to SSR. However, none of these are constraints for you, therefore, SSR is a good option for you. 

For implementing SSR, use the Angular Universal library if you choose Angular. Use Next JS if you plan to use React or Vue JS.

3. On my website, I have HTML content in English. In between, there is a small piece of content in French. I want search engines to pick that up correctly for indexing. I will execute text-to-speech software on that content, and I want the correct pronunciation. Suggest an easy solution.

Web developers should use the HTML “span” tag. Use it to wrap the text in French. Also, add the “lang” attribute to the tag to identify the French language. You can indicate a temporary language change this way, which will take care of search engine indexing. This will also give enough information for text-to-speech software to identify and pronounce the French part of the content. 

See the following code for an example of how you can achieve this:

“

<p>In the French language, <span lang=”fr”>”bonjour”</span>  means “good morning”</p> 

“

4. In my JavaScript-based web app, I have a large operation that consists of a set of asynchronous functions. Should I use “callbacks”? Explain your recommendations.

You should use the JavaScript “promise” object and not “callbacks” for asynchronous JavaScript programming. 

The situation you mention will result in “callbacks” within “callbacks”. Your program will now have a deeply nested function. The readability of the program will reduce, and you will find it harder to debug. JavaScript developers often refer to this situation as the “callback hell”. 

Use the “promise” object since it’s the recommended way for asynchronous JavaScript programming.

5. On my web development project, I want to store a significant amount of files using a client-side storage option. Suggest a simple solution and explain the reasons for the recommendation.

Web developers should use IndexedDB in this case. 

Since you want client-side storage, you need to look at web storage options. Web storage options like “sessionStorage” and “localStorage” aren’t suitable for storing large amounts of data. They involve synchronous operations, which can impact the performance of the web app.

IndexedDB, a JavaScript-based object-oriented database is a better option for storing large data including files. This involves asynchronous operations, therefore, it enables better performance.

6. How should I enhance the web accessibility of the HTML forms on my website?

Use the following approaches to enhance web accessibility of HTML forms:

• You should associate the “<label>” elements specifically with form elements. Assistive technologies can then help users understand what those fields on the form are there for. 
• When you have related form elements, you should put them in a group by using the “<fieldset>” element. You should describe them by using a “<legend>” element. Users can then better navigate the forms.
• Utilize HTML attributes like “autocomplete”. This enhances web accessibility.
• Indicate whether form fields are required by using the HTML attribute “required”.

7. As far as the fold is concerned, is it enough if I limit lazy loading to the below-the-fold content of the web page only?

You should use lazy loading only for the content below the fold. Don’t allow lazy loading for any above-the-fold content. This is an essential rule, however, it’s not enough to follow only this rule. 

Web developers should establish a buffer zone below the fold. The website should start loading the content within this buffer zone before the user can bring them into the viewport by scrolling. Exclude the content in this buffer zone from the scope of lazy loading.

Thinking only about the fold isn’t enough for an even more important reason! You might not have a clear delimitation of the fold since the website might be viewed on different devices. Therefore, identify all the critical content. Keep them outside the scope of lazy loading.

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