Unlocking front-end basics: Some basic Front-End interview questions

Prepare for your Front-End interview with this curated list of basic Front-End interview questions and informative answers. Strengthen your foundational knowledge of web development and increase your chances of success in your upcoming interview.

1. Compare react, angularJS, knockout, ember, viewJS

Certainly, let's compare React, AngularJS, Knockout, Ember.js, and Vue.js across various aspects without plagiarism:

2. Introduction:

  • React:

    • Developed by Facebook, React is a JavaScript library for building user interfaces. It follows a component-based architecture and encourages a unidirectional data flow.
  • AngularJS:

    • Developed by Google, AngularJS is a JavaScript framework for building dynamic web applications. It follows the Model-View-Controller (MVC) architecture and uses two-way data binding.
  • Knockout:

    • Knockout is a lightweight JavaScript library that enables the implementation of the Model-View-ViewModel (MVVM) pattern. It facilitates automatic UI updates when the underlying data changes.
  • Ember.js:

    • Ember.js is a JavaScript framework that follows the convention over configuration (CoC) paradigm. It includes a set of conventions to streamline development and focuses on productivity.
  • Vue.js:

    • Vue.js is a progressive JavaScript framework for building user interfaces. It is known for its simplicity and flexibility and can be incrementally adopted.

3. Data Binding:

  • React:

    • React uses a unidirectional data flow. Data binding is achieved through properties (props) and state. Changes in state trigger re-rendering of components.
  • AngularJS:

    • AngularJS employs two-way data binding, meaning changes in the model or the view automatically reflect in the other. This can simplify code but may impact performance.
  • Knockout:

    • Knockout utilizes declarative bindings to establish a connection between the view and the underlying view model. It supports automatic UI updates based on data changes.
  • Ember.js:

    • Ember.js employs a binding system that facilitates automatic synchronization between templates and underlying data models.
  • Vue.js:

    • Vue.js supports both one-way and two-way data binding. It provides a flexible and efficient reactivity system for handling changes in data.

4. Component-Based Architecture:

  • React:

    • React is renowned for its component-based architecture. Components encapsulate UI and behavior, promoting reusability and maintainability.
  • AngularJS:

    • AngularJS introduced the concept of directives for creating reusable components. However, AngularJS's components are more complex than React's.
  • Knockout:

    • Knockout embraces the Model-View-ViewModel (MVVM) pattern, where components are created using the concept of observable view models.
  • Ember.js:

    • Ember.js emphasizes convention over configuration and uses Ember Components to encapsulate UI and behavior.
  • Vue.js:

    • Vue.js is designed with a component-based architecture. Components in Vue.js are simple and intuitive, making it easy for developers to understand and use.

5. Performance:

  • React:

    • React's virtual DOM efficiently updates only the parts of the actual DOM that have changed, contributing to its performance.
  • AngularJS:

    • Two-way data binding in AngularJS can sometimes impact performance, especially in large applications.
  • Knockout:

    • Knockout's performance is reasonable for small to medium-sized applications, but it may not scale as well as some other frameworks.
  • Ember.js:

    • Ember.js includes features like FastBoot for server-side rendering, contributing to improved performance.
  • Vue.js:

    • Vue.js offers excellent performance, and its reactivity system is optimized for efficient updates.

6. Learning Curve:

  • React:

    • React has a relatively gentle learning curve, especially for those familiar with JavaScript. However, mastering advanced concepts like hooks may take time.
  • AngularJS:

    • AngularJS has a steeper learning curve, particularly due to its comprehensive features and two-way data binding.
  • Knockout:

    • Knockout is relatively easy to learn, especially for developers familiar with JavaScript and the MVVM pattern.
  • Ember.js:

    • Ember.js may have a steeper learning curve due to its strong conventions, but it provides a clear structure for development.
  • Vue.js:

    • Vue.js is known for its ease of integration into existing projects, making it accessible for developers of varying skill levels.

7. Community and Ecosystem:

  • React:

    • React has a massive and active community, with a rich ecosystem of libraries and tools. It is widely adopted in the industry.
  • AngularJS:

    • AngularJS has a large community, but its popularity has decreased since the introduction of Angular (2 and later).
  • Knockout:

    • Knockout has a smaller community compared to React and Angular, and its ecosystem is less extensive.
  • Ember.js:

    • Ember.js has a dedicated community, and its convention-based structure fosters collaboration.
  • Vue.js:

    • Vue.js has a growing and enthusiastic community. It is gaining popularity due to its simplicity and versatility.

8. Flexibility and Extensibility:

  • React:

    • React focuses on being just the view layer, allowing developers to choose other libraries for state management (e.g., Redux) and routing.
  • AngularJS:

    • AngularJS provides a comprehensive framework, including tools for routing, form validation, and dependency injection.
  • Knockout:

    • Knockout is a lightweight library, and developers can integrate it with other libraries as needed.
  • Ember.js:

    • Ember.js includes a set of conventions for various aspects of development, providing a structured and extensible framework.
  • Vue.js:

    • Vue.js strikes a balance between being a complete framework and allowing developers to pick and choose additional libraries.

9. Maintenance and Long-Term Support:

  • React:

    • React is actively maintained, and Facebook provides long-term support. Its modular structure allows for gradual updates.
  • AngularJS:

    • AngularJS is in Long Term Support (LTS) until 2021. Migrating from AngularJS to later versions of Angular may require effort.
  • Knockout:

    • Knockout is still maintained, but its community and updates are not as robust as React or Vue.js.
  • Ember.js:

    • Ember.js has regular releases and provides long-term support. Its conventions make maintenance straightforward.
  • Vue.js:

    • Vue.js is actively maintained, with a strong focus on backward compatibility. Its flexible nature simplifies upgrades.

10. Conclusion:

  • React:

    • Widely adopted, especially for building user interfaces. Known for its simplicity and performance.
  • AngularJS:

    • Still in use, but its popularity has waned. Often chosen for maintaining legacy applications.
  • Knockout:

    • Suitable for smaller projects where simplicity and ease of integration are priorities.
  • Ember.js:

    • Ideal for projects that value convention over configuration and a structured development approach.
  • Vue.js:

    • Gaining popularity rapidly due to its simplicity, flexibility, and efficient reactivity system. Suitable for projects of all sizes.

The choice between these frameworks depends on project requirements, team expertise, and specific preferences. Each has its strengths and is suited to different types of applications.

11. compare different version of angular

Certainly, let's compare different versions of Angular, specifically AngularJS (1.x), Angular (2+), and the later versions (Angular 10+):

12. AngularJS (1.x):

  • Introduction:

    • Released in 2010 by Google.
    • Follows the Model-View-Controller (MVC) architecture.
    • Uses two-way data binding for automatic synchronization between the model and the view.
  • Architecture:

    • Uses controllers, services, and directives for creating components.
    • Two-way data binding simplifies development but may impact performance in large applications.
  • Learning Curve:

    • Steeper learning curve due to its unique concepts and approaches.
    • Large community support but less relevant for modern applications.
  • Performance:

    • Performance limitations in large applications due to two-way data binding.
    • Generally suitable for smaller to medium-sized projects.

13. Angular (2, 4, 5, 6, 7, 8, 9):

  • Introduction:

    • Angular 2 was a complete rewrite, released in 2016, breaking compatibility with AngularJS.
    • Follows the component-based architecture.
  • Architecture:

    • Uses components, services, and modules for structuring applications.
    • Introduced a more modular and scalable architecture.
    • Introduced TypeScript as the primary language.
  • Learning Curve:

    • Angular 2+ has a learning curve but is more modular and scalable.
    • Uses decorators, dependency injection, and TypeScript.
  • Performance:

    • Improved performance compared to AngularJS, especially in large applications.
    • Leverages Ahead-of-Time (AOT) compilation for faster rendering.
  • Features:

    • Introduced reactive programming with RxJS.
    • Improved dependency injection and change detection mechanisms.
    • Enhanced tooling support and a powerful CLI.

14. Angular (10, 11, 12, 13+):

  • Introduction:

    • Angular continues to receive regular updates, with the latest version being Angular 13 (as of the last knowledge update in January 2022).
  • Architecture:

    • Ongoing improvements to the component-based architecture.
    • Enhanced support for lazy loading, enabling better performance.
  • Learning Curve:

    • Incremental updates have made Angular more developer-friendly over time.
    • Angular continues to evolve, with improved documentation and resources.
  • Performance:

    • Ongoing efforts to improve performance and bundle size.
    • Continuous updates to tooling, tree-shaking, and optimization techniques.
  • Features:

    • Continued support for TypeScript and reactive programming.
    • Improvements in Angular CLI, Angular Material, and additional libraries.

15. which framework you like

Decide by yourself

16. what all sorting methods are there with their time and space complexity

Sorting is a fundamental operation in computer science, and various algorithms are employed for this task. Below are some common sorting methods along with their time and space complexity:

17. Bubble Sort:

  • Time Complexity:
    • Worst Case: O(n^2)
    • Best Case (optimized): O(n)
  • Space Complexity:
    • O(1)

18. Selection Sort:

  • Time Complexity:
    • Worst Case: O(n^2)
    • Best Case: O(n^2)
  • Space Complexity:
    • O(1)

19. Insertion Sort:

  • Time Complexity:
    • Worst Case: O(n^2)
    • Best Case (sorted input): O(n)
  • Space Complexity:
    • O(1)

20. Merge Sort:

  • Time Complexity:
    • Worst Case: O(n log n)
    • Best Case: O(n log n)
  • Space Complexity:
    • O(n)

21. Quick Sort:

  • Time Complexity:
    • Worst Case: O(n^2) (rare, with poor pivot selection)
    • Best Case: O(n log n)
  • Space Complexity:
    • O(log n) - in-place variant (Hoare's partition scheme)

22. Heap Sort:

  • Time Complexity:
    • Worst Case: O(n log n)
    • Best Case: O(n log n)
  • Space Complexity:
    • O(1) - in-place sorting

23. Radix Sort:

  • Time Complexity:
    • Worst Case: O(kn) where k is the number of digits in the largest number
    • Best Case: O(kn)
  • Space Complexity:
    • O(n + k)

24. Counting Sort:

  • Time Complexity:
    • Worst Case: O(n + k) where k is the range of input
    • Best Case: O(n + k)
  • Space Complexity:
    • O(k)

25. Bucket Sort:

  • Time Complexity:
    • Worst Case: O(n^2) if each element is placed in the same bucket
    • Best Case: O(n + k) when elements are uniformly distributed across buckets
  • Space Complexity:
    • O(n + k)

26. Shell Sort:

  • Time Complexity:
    • Worst Case: O(n log^2 n) or O(n^(3/2)) depending on the gap sequence
    • Best Case: O(n log n)
  • Space Complexity:
    • O(1)

These complexities are indicative and may vary based on the implementation and specific scenarios. It's important to choose a sorting algorithm based on the characteristics of the data set and the requirements of the task at hand. Each sorting algorithm has its strengths and weaknesses, and the choice depends on factors such as the size of the dataset, stability requirements, and whether it needs to be performed in-place.

27. How you will improve performance of website

Improving the performance of a website involves optimizing various aspects to ensure faster loading times, better user experience, and efficient resource utilization. Here are some strategies to enhance website performance without plagiarism:

28. Optimize Images:

  • Compression: Compress images to reduce file size without compromising quality.
  • Lazy Loading: Load images only when they come into the user's viewport.

29. Minimize HTTP Requests:

  • Combine Files: Reduce the number of HTTP requests by combining CSS and JavaScript files.
  • CSS Sprites: Combine small images into a single image sprite to minimize HTTP requests.

30. Enable Browser Caching:

  • Cache-Control Headers: Leverage cache-control headers to instruct browsers to cache static resources.
  • ETags: Implement entity tags to validate whether a resource has changed before fetching.

31. Optimize CSS and JavaScript:

  • Minification: Minify CSS and JavaScript files to remove unnecessary characters and whitespace.
  • Asynchronous Loading: Use asynchronous loading for non-blocking rendering.

32. Use Content Delivery Network (CDN):

  • CDN Integration: Distribute static assets across a network of servers globally for faster content delivery.

33. Reduce Server Response Time:

  • Optimize Code: Ensure server-side code is optimized and executes efficiently.
  • Caching: Implement server-side caching to reduce the time to generate responses.

34. Prioritize Above-the-Fold Content:

  • Critical Rendering Path: Prioritize the loading of above-the-fold content for quicker perceived performance.

35. Optimize Fonts:

  • Subset Fonts: Use only the characters needed to display content to reduce font file size.
  • Asynchronous Loading: Load fonts asynchronously to prevent blocking rendering.

36. Minimize Redirects:

  • Reduce Redirects: Minimize the number of redirects as each redirect adds to the page load time.

37. Implement GZIP Compression:

  • GZIP: Enable GZIP compression to reduce the size of files transmitted over the network.

38. Optimize Database Queries:

  • Indexing: Ensure that databases are properly indexed for efficient query performance.
  • Database Caching: Implement caching for frequently accessed data.

39. Use Efficient Content Delivery:

  • Optimized Media Hosting: Use efficient media hosting solutions for videos and other media content.
  • Adaptive Images: Serve different image sizes based on the user's device.

40. Monitor and Analyze Performance:

  • Performance Monitoring Tools: Use tools like Google PageSpeed Insights, Lighthouse, or WebPageTest to identify bottlenecks.
  • Regular Audits: Conduct regular performance audits to address new issues.

41. Implement Progressive Web App (PWA) Features:

  • Offline Support: Implement service workers for offline support and quicker load times on subsequent visits.

42. Optimize Third-Party Scripts:

  • Evaluate Third-Party Dependencies: Minimize the use of third-party scripts and evaluate their impact on performance.

43. Implement Server-Side Rendering (SSR) or Static Site Generation (SSG):

  • SSR/SSG: Render pages on the server to reduce client-side rendering time.

44. Mobile Optimization:

  • Responsive Design: Ensure the website is optimized for various screen sizes and devices.
  • Mobile-First Approach: Design and optimize for mobile users first.

45. Consider Using a Performance Budget:

  • Set Budgets: Establish performance budgets for various metrics and stick to them during development.

46. Regularly Update Dependencies:

  • Dependency Management: Keep frameworks, libraries, and plugins up-to-date to benefit from performance improvements and security patches.

Implementing a combination of these strategies can significantly enhance the overall performance of a website. It's essential to regularly monitor and adjust these optimizations based on changes in content, user behavior, and technological advancements.

47. If a website running slow how will you debug it for root cause.

Debugging a slow website involves identifying and addressing various factors affecting performance. Here's a systematic approach to diagnose and troubleshoot the root causes of slow website performance:

48. Performance Monitoring Tools:

  • Utilize tools like Google PageSpeed Insights, Lighthouse, WebPageTest, or browser developer tools (e.g., Chrome DevTools) to analyze the website's performance metrics.

49. Identify Slow Components:

  • Use performance profiling tools to identify specific elements (scripts, styles, images, etc.) causing delays.
  • Check the waterfall chart to visualize the loading sequence and identify bottlenecks.

50. Network Analysis:

  • Examine network requests to identify slow-loading resources.
  • Check for large or uncompressed images, long server response times, and unnecessary redirects.

51. Browser Developer Tools:

  • Use the browser's developer tools to inspect network activity, console errors, and performance profiles.
  • Review console logs for potential JavaScript errors or warnings affecting performance.

52. Server-Side Performance:

  • Check server response times and latency using tools like Pingdom or server monitoring software.
  • Optimize server-side code, database queries, and caching mechanisms.

53. Cache Analysis:

  • Review caching strategies for static assets, leveraging browser caching and CDN caching where applicable.
  • Verify if proper cache headers are set and utilized.

54. Minification and Compression:

  • Ensure CSS, JavaScript, and HTML files are minified to reduce file sizes.
  • Enable gzip compression for text-based resources to reduce transfer times.

55. Database Optimization:

  • Optimize database queries and ensure proper indexing.
  • Evaluate the performance of database transactions and connections.

56. Content Delivery Network (CDN):

  • Implement or optimize CDN usage to distribute content globally and reduce latency.

57. Third-Party Scripts:

  • Review and assess the impact of third-party scripts on the website's performance.
  • Consider asynchronous loading for non-essential third-party components.

58. Evaluate JavaScript Execution:

  • Assess the execution time of JavaScript code and identify performance-intensive functions.
  • Consider code splitting and lazy loading for non-essential JavaScript.

59. Content Optimization:

  • Optimize and compress images using appropriate formats (WebP, JPEG, etc.).
  • Minimize the use of large media files and consider lazy loading for images.

60. Monitoring Server Resources:

  • Check server resource utilization, including CPU, memory, and disk usage.
  • Ensure the server has adequate resources to handle the website's load.

61. Content Rendering:

  • Examine how content is rendered on the page, focusing on the Critical Rendering Path.
  • Optimize the order in which resources are loaded to prioritize critical content.

62. Use Performance Budgets:

  • Set performance budgets for critical metrics like page load time, and adhere to them during development.

63. Continuous Monitoring:

  • Implement continuous monitoring to detect performance regressions.
  • Set up alerts for key performance indicators to address issues promptly.

64. User Feedback:

  • Gather user feedback on performance issues through analytics or direct user interactions.
  • Prioritize improvements based on the impact on user experience.

65. Implementing Fixes:

  • Address identified issues systematically, starting with the most critical components affecting performance.
  • Re-test and monitor performance after implementing fixes.

66. Documentation and Communication:

  • Document findings, solutions, and improvements for future reference.
  • Communicate improvements to the development team and stakeholders.

By following this comprehensive approach, you can identify and address the root causes of a slow website, leading to improved performance and a better user experience. Regular monitoring and proactive optimization are key to maintaining optimal website performance over time.

67. What all things you use in chrome dev tools.

See More here

Google Chrome Developer Tools is a powerful set of features built into the Chrome browser that assists developers in debugging, optimizing, and understanding web pages. Here are various tools and features available in Chrome DevTools:

68. Elements Panel:

  • Inspect Element: Allows you to inspect and edit HTML and CSS on the fly.
  • DOM Tree: Visualizes the document object model, showing the hierarchy of HTML elements.
  • Styles Pane: Edit and experiment with CSS styles applied to elements.

69. Console:

  • JavaScript Console: Logs errors, warnings, and messages generated by JavaScript code.
  • Interactive Command Line: Allows you to execute JavaScript commands and manipulate the page.

70. Sources Panel:

  • Debugger: Set breakpoints, step through code, and analyze the call stack.
  • File Navigator: Explore and debug JavaScript and other resources.
  • Snippets: Save and run custom blocks of JavaScript code.

71. Network Panel:

  • Network Requests: Monitors HTTP requests and responses, including headers, status, and timing.
  • Waterfall Chart: Visualizes the loading sequence of resources.
  • Performance Analysis: Evaluate resource loading times and bottlenecks.

72. Performance Panel:

  • Timeline: Records and analyzes events related to the loading and execution of a page.
  • Frame Viewer: Visualizes rendering performance and frame rates.
  • JavaScript Profiling: Profiles and analyzes JavaScript execution.

73. Memory Panel:

  • Heap Snapshot: Captures and analyzes JavaScript heap memory usage.
  • Allocation Timeline: Shows memory allocation events over time.

74. Application Panel:

  • Service Workers: Inspects and debugs service workers for progressive web apps.
  • Manifest: Examines the web app manifest for PWA features.
  • Clear Storage: Manages local storage, session storage, and other types of storage.

75. Security Panel:

  • Security Overview: Displays security-related information, including HTTPS status.
  • Certificate Viewer: Inspects SSL certificates.
  • Mixed Content: Flags insecure content on HTTPS pages.

76. Audits Panel:

  • Lighthouse: Performs audits and provides insights on performance, accessibility, SEO, and more.
  • Performance Budgets: Sets and monitors performance budgets.

77. Console Drawer:

  • Console Snippets: Saves and runs frequently used code snippets.
  • Command Menu: Quickly access and execute commands.

78. Device Mode:

  • Responsive Design: Simulates various device sizes and resolutions.
  • Network Conditions: Simulates different network conditions for testing.

79. Animations Panel:

  • Inspect Animations: Visualizes and debugs CSS animations and transitions.
  • Timeline for Animations: Provides a timeline view of CSS animations.

80. Application Tab:

  • Manifest: Inspects the web app manifest.
  • Service Workers: Registers and debugs service workers.
  • Cache Storage: Manages and inspects caches.

81. More Tools:

  • Coverage: Analyzes how much of your JavaScript and CSS is used by the page.
  • Performance Monitor: Monitors real-time performance metrics.
  • Remote Devices: Inspects and debugs pages on connected remote devices.

82. Experimental Features:

  • Layers Panel: Visualizes the rendering layers on a page.
  • Performance Metrics: Displays additional metrics related to performance.

83. What is TTFB, what it depicts.

TTFB stands for Time To First Byte. It is a web performance metric that measures the time taken from the moment a user makes an HTTP request to a server to the point when the server sends back the first byte of data in response. TTFB is a critical indicator of the server's responsiveness and the efficiency of the initial stages of the web page loading process.

84. Key Aspects of TTFB:

  • Server Responsiveness:

    • TTFB reflects how quickly a web server processes and responds to a user's request.
    • A low TTFB indicates a responsive server, while a high TTFB suggests potential delays in processing the request.
  • Network Latency:

    • TTFB includes the time spent on network communication between the user's device and the server.
    • Higher network latency can contribute to an increased TTFB.
  • Server Processing Time:

    • TTFB encompasses the time taken by the server to generate and begin sending the first byte of the response.
    • Server-side processing time, database queries, and other server-related tasks influence this component.

85. What TTFB Depicts:

  • User Experience:

    • TTFB directly impacts the user experience, as a fast TTFB contributes to quicker page loading.
    • Users perceive a faster-loading website when the server responds promptly.
  • SEO Impact:

    • Search engines consider TTFB as one of the factors for determining website speed.
    • A faster TTFB can positively influence search engine rankings, as speed is a crucial SEO metric.
  • Server Health:

    • TTFB can be an indicator of the health and efficiency of a web server.
    • Regularly monitoring TTFB helps identify server issues and optimize server performance.
  • Optimization Opportunities:

    • A high TTFB may indicate potential areas for optimization, such as server configuration, database queries, or resource loading strategies.
    • Developers can use TTFB data to identify and address performance bottlenecks.

86. TTFB Measurement:

TTFB is measured in milliseconds (ms), and it is typically broken down into the following components:

  • DNS Resolution Time: Time taken to resolve the domain name to an IP address.
  • Connection Time: Time spent establishing a connection to the server.
  • SSL/TLS Handshake Time (if applicable): Time taken to negotiate a secure connection.
  • Server Processing Time: Time spent by the server processing the request and generating the initial response.

87. How will you profile your web application

Profiling a web application involves analyzing its performance to identify bottlenecks, inefficiencies, and areas for optimization. Here is a step-by-step guide on how to profile your web application without plagiarism:

88. Understand the Goals:

  • Define the goals of profiling. Are you looking to improve page load times, reduce server response times, or optimize client-side rendering?

89. Select Profiling Tools:

  • Choose the appropriate profiling tools based on your goals.
  • Common tools include browser developer tools, server-side profilers, and third-party performance monitoring services.

90. Timeline and JavaScript Profiling:

  • Record Performance:
    • Use the timeline recording feature to capture events related to loading, scripting, rendering, and painting.
    • Examine the timeline for long tasks, forced synchronous layouts, and excessive scripting.
    • Utilize the JavaScript profiler to identify performance-intensive functions.

91. Memory Profiling:

  • Memory Usage:
    • Monitor memory usage to identify memory leaks or inefficient memory management.
    • Use the memory profiler to take snapshots and compare memory states.

92. Audits and Lighthouse:

  • Audits Panel:
    • Run audits in the "Audits" panel to get insights into performance, accessibility, SEO, and best practices.
  • Lighthouse:
    • Use Lighthouse, a performance testing tool integrated into many browsers or available as a standalone tool.

93. Server-Side Profiling:

  • Server Logs:
    • Analyze server logs to identify slow queries, server errors, and response times.
    • Consider using server-side profiling tools or profiling extensions for your server framework.

94. Real User Monitoring (RUM):

  • Implement RUM Tools:
    • Integrate Real User Monitoring tools to collect data from actual users.
    • Analyze user interactions, page load times, and overall user experience.

95. Third-Party Services:

  • Performance Monitoring Services:
    • Use third-party services like New Relic, Datadog, or Sentry for comprehensive performance monitoring.
    • These services often provide detailed insights into application performance, errors, and user experience.

96. Identify and Address Issues:

  • Review Findings:
    • Review the profiling data and identify performance bottlenecks and issues.
  • Prioritize Optimization:
    • Prioritize optimizations based on the severity and impact of identified issues.

97. Implement and Test:

  • Optimization Strategies:
    • Implement optimization strategies, whether it involves code changes, server configuration updates, or resource optimizations.
  • A/B Testing:
    • A/B test optimizations to ensure they positively impact performance without introducing new issues.

98. Monitor and Iterate:

  • Continuous Monitoring:
    • Continuously monitor application performance to identify and address new issues.
    • Iterate on the profiling process to refine strategies and improve overall performance.

99. What is good code according to you.

Writing good code is a subjective and evolving concept, but there are several principles and practices that are generally considered indicative of high-quality code. Here are some characteristics of good code:

100. Readability:

  • Code should be easy to read and understand.
  • Use meaningful variable and function names.
  • Follow a consistent coding style.

101. Modularity:

  • Break code into small, independent modules or functions.
  • Encapsulate logic to promote reusability.
  • Follow the Single Responsibility Principle.

102. Maintainability:

  • Code should be easy to maintain and update.
  • Avoid unnecessary complexity and convoluted structures.
  • Add comments and documentation where necessary.

103. Efficiency:

  • Optimize code for performance where applicable.
  • Use appropriate algorithms and data structures.
  • Avoid unnecessary resource consumption.

104. Scalability:

  • Code should be designed to scale with increased demand.
  • Consider the potential growth of the application.

105. Consistency:

  • Follow consistent coding conventions.
  • Use a consistent indentation style.
  • Ensure a consistent approach to error handling.

106. Flexibility:

  • Design code to be adaptable to changes.
  • Avoid hardcoding values that may change frequently.
  • Embrace the Open/Closed Principle.

107. Testability:

  • Write code that is easy to test.
  • Use unit tests and automation testing where possible.
  • Follow the Arrange-Act-Assert pattern.

108. Security:

  • Write code with security considerations in mind.
  • Validate input data and avoid vulnerabilities.
  • Keep dependencies and libraries up to date.

109. Collaboration:

  • Write code that is easy for others to collaborate on.
  • Use version control systems effectively.
  • Provide clear and concise commit messages.

110. Error Handling:

  • Handle errors gracefully and informatively.
  • Avoid using generic error messages that might expose sensitive information.
  • Log errors for debugging purposes.

111. Conservation of Resources:

  • Use system resources judiciously.
  • Close connections and release resources appropriately.
  • Optimize memory usage and garbage collection.

112. Versioning:

  • Use version control systems to manage code versions.
  • Clearly label and document releases.

113. DRY Principle (Don't Repeat Yourself):

  • Avoid duplicating code.
  • Encapsulate repeated logic in functions or modules.


  • Use comments sparingly and focus on explaining why, not what.
  • Avoid unnecessary comments that duplicate the code.

115. Continuous Improvement:

  • Be open to feedback and continuously strive to improve code quality.
  • Refactor code when necessary to maintain high standards.

116. Have you used testing libraries like jest, mocha, protractor, selenium etc.

See more here

Certainly! Let's compare Jest, Mocha, Protractor, and Selenium based on their primary use cases and features:

117. Jest:

  • Primary Use Case:
    • Predominantly used for testing JavaScript code, especially in React applications.
  • Key Features:
    • Zero Configuration: Jest comes with a low-config setup, making it easy to get started.
    • Snapshot Testing: Captures and compares snapshots of rendered components.
    • Built-in Mocking: Provides built-in mocking capabilities for functions, modules, and timers.
    • Code Coverage: Includes built-in code coverage reporting.
  • Consider Jest When:
    • Testing React applications or JavaScript projects with minimal configuration.
    • Snapshot testing and built-in mocking are important.

118. Mocha:

  • Primary Use Case:
    • General-purpose JavaScript testing framework for both front-end and back-end applications.
  • Key Features:
    • Flexible Configuration: Highly configurable, allowing the choice of assertion libraries and customization of the test runner.
    • Asynchronous Testing: Supports asynchronous testing through callback functions, promises, or async/await.
    • Hooks: Provides hooks (before, after, beforeEach, afterEach) for setting up and tearing down test environments.
  • Consider Mocha When:
    • Needing flexibility in configuration and choosing your assertion library.
    • Extensive hooks for test setup and teardown are required.

119. Protractor:

  • Primary Use Case:
    • Designed specifically for end-to-end testing of Angular applications.
  • Key Features:
    • Angular-Specific: Understands Angular-specific elements and waits for Angular to stabilize before performing actions.
    • Declarative Syntax: Tests are written in a declarative, behavior-driven syntax using Jasmine.
    • Automatic Waiting: Implicitly waits for Angular promises to resolve, reducing the need for explicit waits.
  • Consider Protractor When:
    • Testing Angular applications.
    • Leveraging a framework that aligns with behavior-driven development.

120. Selenium:

  • Primary Use Case:
    • Cross-browser testing of web applications.
  • Key Features:
    • Cross-Browser Testing: Allows testing web applications on various browsers and platforms.
    • Supports Multiple Languages: Selenium supports multiple programming languages like Java, Python, C#, etc.
    • Flexibility: Suitable for testing web applications built with any technology.
  • Consider Selenium When:
    • Conducting cross-browser testing.
    • Testing web applications built with different technologies.

121. Summary:

  • Jest: Ideal for React applications, snapshot testing, and minimal configuration.
  • Mocha: General-purpose for both front-end and back-end testing, offering flexibility in configuration.
  • Protractor: Specifically designed for end-to-end testing of Angular applications with an Angular-specific syntax.
  • Selenium: Widely used for cross-browser testing of web applications, supporting multiple programming languages.

The choice between these tools depends on your project requirements, the technologies used, and the level of configurability and specialization needed for your testing scenarios.

122. what is difference between snapshot testing, units testing, integration testing

Snapshot testing, unit testing, and integration testing are different levels of testing in software development, each serving a specific purpose. Let's explore the differences between them:

123. Snapshot Testing:

  • Purpose:
    • To capture and compare snapshots of rendered components or data structures to identify unintended changes.
  • Key Characteristics:
    • Captures a representation (snapshot) of the output or state of a component.
    • Compares the captured snapshot with a reference snapshot to detect any changes.
  • Example:
    • Commonly used in front-end testing, especially with frameworks like Jest. It is often employed for React component testing to ensure that UI components render consistently.

124. Unit Testing:

  • Purpose:
    • To test individual units or components of code in isolation to ensure they function as expected.
  • Key Characteristics:
    • Focuses on testing the smallest parts of the software, such as functions, methods, or classes.
    • Isolation is key; dependencies are usually mocked or replaced with test doubles.
  • Example:
    • Testing a specific function or method in isolation from the rest of the codebase. It ensures that each unit works correctly on its own.

125. Integration Testing:

  • Purpose:
    • To verify that multiple units or components work together as expected when integrated.
  • Key Characteristics:
    • Tests interactions between different units to uncover issues that may arise from their integration.
    • Actual dependencies are used, and the test simulates the behavior of the integrated system.
  • Example:
    • Testing the interaction between a database and the application layer to ensure that data is retrieved and processed correctly.

126. Differences:

  • Scope:

    • Snapshot Testing: Focuses on capturing and comparing the output of components.
    • Unit Testing: Concentrates on testing individual units or functions in isolation.
    • Integration Testing: Verifies the collaboration and interaction of multiple units.
  • Isolation:

    • Snapshot Testing: Primarily concerned with the visual representation or state of a component.
    • Unit Testing: Requires isolating the unit being tested from external dependencies.
    • Integration Testing: Involves testing the combined behavior of interconnected units.
  • Dependencies:

    • Snapshot Testing: Often independent of dependencies or relies on mocked data.
    • Unit Testing: Dependencies are often mocked or replaced to isolate the unit under test.
    • Integration Testing: Involves the actual use of dependencies to simulate real-world interactions.
  • Purpose:

    • Snapshot Testing: Ensures visual consistency and identifies unintended UI changes.
    • Unit Testing: Validates the correctness of individual units in isolation.
    • Integration Testing: Verifies that integrated units collaborate correctly.

127. Conclusion:

Snapshot testing, unit testing, and integration testing serve distinct purposes in the testing process. Snapshot testing is concerned with capturing visual representations, unit testing focuses on individual components in isolation, and integration testing ensures that these components work seamlessly together. Depending on your testing needs, you may use one or a combination of these testing levels to ensure the robustness and correctness of your software.

128. what is functional/behavioral testing vs units testing

Functional testing, behavioral testing, and unit testing are different levels of testing in software development, each focusing on specific aspects of the software's behavior and functionality.

129. Functional Testing:

  • Purpose:
    • To verify that the software functions as intended from end to end.
  • Key Characteristics:
    • Evaluates the system's compliance with functional requirements and specifications.
    • Involves testing the complete and integrated application.
    • Encompasses various testing types, including smoke testing, regression testing, and acceptance testing.
  • Example:
    • Testing the entire login process of a web application, including user input, authentication, and navigation.

130. Behavioral Testing:

  • Purpose:
    • To assess how the software behaves in response to various inputs and conditions.
  • Key Characteristics:
    • Focuses on the observable behavior of the system from the user's perspective.
    • Includes scenarios that test user interactions, workflows, and system responses.
    • Often associated with Behavior-Driven Development (BDD) principles, using tools like Cucumber or SpecFlow.
  • Example:
    • Writing test scenarios that describe the expected behavior of a user interacting with a feature, such as adding items to a shopping cart.

131. What is basic role of frontend developer

A frontend developer represents end user. He should think in respect to end user who is gonna use the application.

132. What is different between UI and UX

UI (User Interface) and UX (User Experience) are closely related but distinct aspects of the overall design process. Here's a concise differentiation between UI and UX:

133. UI (User Interface):

  • Focus: UI design primarily concentrates on the look and feel of a product.
  • Components: Involves the design of visual elements, such as buttons, icons, colors, and layout.
  • Goal: Aims to create an aesthetically pleasing and visually intuitive interface.
  • Execution: UI designers work on the surface-level design elements that users interact with directly.

134. UX (User Experience):

  • Focus: UX design is concerned with the overall user journey and satisfaction.
  • Components: Encompasses the entire user experience, including interactions, navigation, and usability.
  • Goal: Strives to create a seamless and enjoyable experience for the user throughout their interaction with the product.
  • Execution: UX designers work on understanding user needs, conducting research, and optimizing the overall usability and satisfaction.

135. What is server side rendering, how it helps it increases our SEO index

See more here SSR

Server-Side Rendering (SSR) is a technique used in web development to render web pages on the server before sending them to the client's browser. Unlike traditional client-side rendering, where the browser is responsible for rendering the page, SSR performs the rendering on the server and sends the fully rendered HTML to the client.

136. Benefits of Server-Side Rendering:

  • Improved Page Load Time:

    • SSR reduces the initial page load time by sending pre-rendered HTML to the client, enhancing the user experience.
  • SEO (Search Engine Optimization):

    • SSR is beneficial for SEO because search engines can crawl and index the fully rendered content, improving the visibility of the web pages in search results.
  • Social Media Sharing:

    • When sharing links on social media platforms, SSR ensures that the shared content includes the complete HTML, enhancing the appearance of links and previews.
  • Performance on Low-Powered Devices:

    • Devices with limited processing power benefit from SSR as they receive pre-rendered HTML, reducing the client-side processing load.

137. How SSR Improves SEO:

  • Content Accessibility:

    • Search engine bots can easily access and index the content, as the server sends fully rendered HTML, making the content readily available for crawling.
  • Meta Tags and Descriptions:

    • SSR allows dynamic generation of meta tags and descriptions on the server, ensuring that search engines receive accurate and relevant information about the page.
  • Indexable Content:

    • The HTML content is fully rendered on the server, allowing search engines to index the content accurately, including text, images, and other elements.
  • Faster Time-to-Index:

    • Since the server sends a fully rendered page, search engines can quickly index the content without waiting for client-side rendering, leading to faster time-to-index.

138. What is monkey-patching

Monkey-patching is a programming technique where existing code or modules are dynamically modified or extended at runtime. This involves altering or adding functions, methods, or attributes to modify the behavior of a program without changing its original source code. Monkey-patching is often used for debugging, testing, or to add temporary fixes to third-party code. However, it should be employed with caution, as it can lead to unexpected behavior and is generally considered a last resort due to its potential for introducing hard-to-maintain and error-prone code.

Published On: 2024-01-17