What are the hardest Web Dev questions?

Once in a while, we find ourselves in the hot seat on an interview session with hopes to conquer new heights in our Web Dev career. While mostly prepared, one cannot know what the person on the other end might ask. We are caught off guard, our minds race, and we try to come up with the best answer possible.

I collected some of the hardest web development questions out there in the vast spaces on the internet and here are the toughest:

1. What is the difference between HTTP/1.1 and HTTP/2: 
   HTTP/1.1 is the older version of the HTTP protocol. It is a text-based protocol that is relatively slow and inefficient. HTTP/2 is the newer version of the HTTP protocol. It is a binary-based protocol that is much faster and more efficient.
   
2. What are Cookies and local storage: 
   Cookies are small pieces of data that are stored on the user’s computer. They are used to store information about the user, such as their login status or their shopping cart contents. Local storage is a more persistent form of storage that is stored on the user’s computer. It is used to store larger amounts of data that need to be available even after the user closes their browser.
   
3. Explain what is AJAX: 
   AJAX, or asynchronous JavaScript and XML, is a technique that allows web pages to update without having to reload the entire page. This is done by sending small requests to the server in the background, and then updating the page with the new data.
   
   AJAX is used to create more interactive and responsive web applications. For example, you might use AJAX to update a chat application without having to refresh the entire page. You could also use AJAX to update a stock ticker without having to reload the entire page.
   Here is an analogy that might help you to understand how AJAX works:
   
   Imagine that you are playing a video game. You are in the middle of a level, and you need to get to the next level. However, you don’t want to have to start the entire level over again. Instead, you can use AJAX to update the page with the new level. This will allow you to continue playing the game without having to reload the entire page.
   
   Here are some examples of websites that use AJAX:
   • Google Maps
   • Gmail
   • Facebook
   • Twitter
   • Netflix
     
4. What is a Content delivery network (CDN): 
   A CDN, or content delivery network, is a group of servers that are distributed around the world. These servers work together to deliver web content to users more quickly and efficiently.
   
   When you visit a website, your computer first has to request the content from the website’s server. If the website is using a CDN, the content will be delivered to you from the server that is closest to you. This means that the content will travel a shorter distance, which will make it load faster.
   
   CDNs are especially helpful for websites that have a lot of traffic. For example, if you visit a popular news website, the website’s server might be overloaded with requests. A CDN can help to alleviate this problem by distributing the load across multiple servers.
   
5. How to optimize a website loading speed?
   • Minify your JavaScript and CSS files. 
     This means removing unnecessary whitespace, comments, and other non-essential code from your files. This can help to reduce the size of your files, which can improve the loading time of your page.
   • Use a content delivery network (CDN). 
     A CDN is a network of servers that are distributed around the world. When you use a CDN, your web pages are hosted on these servers, which can help to improve the loading time of your pages for users who are located far away from your web server.
   • Compress your images. 
     This means reducing the size of your images without sacrificing too much quality. This can help to reduce the size of your pages, which can improve the loading time of your pages.
   • Lazy load your images. 
     Lazy loading means that images are not loaded until they are visible on the screen. This can help to improve the loading time of your pages, especially if your pages contain a lot of images.
   • Use a caching plugin. 
     A caching plugin can help to store static files, such as images and CSS files, on the user’s computer. This can help to improve the loading time of your pages, especially for users who visit your site frequently.
   • Use a performance testing tool. 
     There are a number of performance testing tools available that can help you to measure the loading time of your pages. These tools can help you to identify areas where you can improve the loading time of your pages.
     
6. What are the most common web security threats?
   
   • Phishing: 
     Phishing is a type of social engineering attack that involves sending emails or text messages that appear to be from a legitimate source. The emails or text messages will often contain a link that, when clicked, will take the user to a fake website that looks like the real website. Once the user enters their personal information on the fake website, the attacker can steal it.
     
   • Malware: 
     Malware is software that is designed to harm a computer system. Malware can be installed on a computer system through a variety of ways, such as clicking on a malicious link, opening an infected attachment, or downloading a file from an untrusted source. Once malware is installed on a computer system, it can steal personal information, damage files, or even take control of the system.
     
   • SQL injection: 
     SQL injection is a type of attack that involves injecting malicious code into a SQL query. This can be done by entering malicious code into a form field on a website or by exploiting a vulnerability in a web application. Once the malicious code is injected, it can be used to steal data from the database or to gain unauthorized access to the system.
     
   • Cross-site scripting (XSS): 
     Cross-site scripting (XSS) is a type of attack that involves injecting malicious code into a web page. This can be done by exploiting a vulnerability in a web application or by tricking a user into clicking on a malicious link. Once the malicious code is injected, it can be used to steal cookies, session tokens, or other sensitive information from the user’s browser.
     
   • Denial-of-service (DoS) attack: A denial-of-service (DoS) attack is an attack that is designed to make a website or web application unavailable to legitimate users. This can be done by flooding the website or web application with traffic, or by exploiting a vulnerability in the system.
     
7. How would you implement a secure web application?
   
   • Use HTTPS. 
     HTTPS is a secure protocol that encrypts all communication between the client and the server. This helps to protect sensitive data, such as passwords and credit card numbers.
     
   • Implement strong authentication and authorization. 
     This means using strong passwords, multi-factor authentication, and role-based access control to restrict access to sensitive data.
     
   • Sanitize all user input. 
     This means checking all input from users for malicious code before it is processed by the application. This helps to protect against cross-site scripting (XSS) attacks and other types of code injection attacks.
     
   • Use a content security policy (CSP). 
     A CSP is a security header that can be used to restrict the types of content that can be loaded by a web application. This helps to protect against cross-site scripting (XSS) attacks and other types of attacks that involve loading malicious content into a web application.
     
   • Keep the application up to date. 
     Software vendors often release security patches for their applications. It is important to keep the application up to date with the latest patches to protect against known vulnerabilities.
     
   • Use a web application firewall (WAF). 
     A WAF is a device that can be used to filter traffic to a web application. This helps to protect against common attacks, such as SQL injection and denial-of-service attacks.
     
   • Perform regular security assessments. 
     It is important to perform regular security assessments of the web application to identify and fix any security vulnerabilities.
     
8. What are the different ways to test a web application?
   
   • Manual testing: 
     This is the most basic type of testing, and it involves manually checking the application for errors. This can be done by using a variety of tools, such as a web browser, a text editor, and a debugger.
     
   • Unit testing: 
     This type of testing involves testing individual units of code, such as functions or methods. This helps to ensure that the code is working correctly and that it is not introducing any errors.
     
   • Integration testing: 
     This type of testing involves testing how different units of code interact with each other. This helps to ensure that the application is working as a whole and that there are no errors in the communication between different parts of the application.
     
   • System testing: 
     This type of testing involves testing the entire application as a whole. This helps to ensure that the application is meeting all of its requirements and that it is working correctly in all of its intended use cases.
     
   • Acceptance testing: 
     This type of testing is performed by the customer or end user to ensure that the application meets their needs. This type of testing is typically performed after the application has been fully developed and tested.
     
   • Performance testing: 
     This type of testing is used to measure the performance of the application. This includes testing the application’s response time, its scalability, and its ability to handle a large number of users.
     
   • Security testing: 
     This type of testing is used to identify and fix security vulnerabilities in the application. This includes testing for cross-site scripting (XSS) attacks, SQL injection attacks, and other types of attacks.
     
   • Usability testing: 
     This type of testing is used to ensure that the application is easy to use and that it meets the needs of its users. This type of testing is typically performed by users who are not familiar with the application.
     
9. What are the best practices for writing maintainable and scalable web code?
   
   • Use clear and consistent coding conventions. 
     This will make the code easier to read and understand, and it will also make it easier to find and fix errors.
     
   • Write modular code. 
     This means breaking the code down into smaller, self-contained modules. This will make the code easier to understand and maintain, and it will also make it easier to reuse the code in other projects.
     
   • Use comments to explain the code. 
     This will make the code easier to understand for both you and other developers.
     
   • Use descriptive variable names. 
     This will make the code easier to read and understand.
     
   • Use white space effectively. 
     This will make the code easier to read and understand.
     
   • Test the code thoroughly. 
     This will help to ensure that the code is working correctly and that it is free of errors.
     
   • Use a version control system. 
     This will allow you to track changes to the code and to revert to previous versions of the code if necessary.
     
   • Document the code. 
     This will make it easier for other developers to understand the code and to make changes to it.