Full Stack Interview Questions and Answers- Part 5

Full Stack Interview Questions and Answers- Part 5
Looking to land a job as a full stack developer? You’ll need to prepare for interviews that test both your front-end and back-end skills. That’s where this blog can help. We’ve put together a detailed list of full stack interview questions and answers to help you get ready. These questions are based on real interviews and are commonly asked by hiring managers. Topics include HTML, CSS, JavaScript, frameworks like React or Angular, server-side tools like Node.js, and databases such as MongoDB and SQL.

We explain each answer in simple terms so you can understand the concepts clearly. Whether you’re switching careers or trying to level up in your current job, this guide is a great way to start.

Answer:

The differences between the forward() method of RequestDispatcher and sendRedirect() method of HttpServletResponse interface are given below:

forward() method sendRedirect() method
Works at server side. Works at client side.
Sends the same request and response objects to another servlet. Sends a new request.
Work within the server only. Used within and outside the server.
Example: request.getRequestDispacher(“servlet2”).forward(request,response); Example: response.sendRedirect(“servlet2”);

Answer:

A JavaScript Promise is an object that represents the eventual completion or failure of an asynchronous operation. It is a mechanism to handle asynchronous operations more elegantly and manage their results. Promises are commonly used when dealing with tasks like network requests, file operations, and other asynchronous tasks.

A Promise can be in one of three states:

  1. Pending: This is the initial state when a Promise is created. It means that the asynchronous operation has not yet completed or failed.
  2. Fulfilled: A Promise enters this state when the asynchronous operation is successfully completed. The Promise now holds the result value.
  3. Rejected: If the asynchronous operation encounters an error, the Promise transitions to the rejected state. The Promise now holds the reason for the failure.

Answer:

A Request Dispatcher is an interface provided by servlet containers (like Tomcat) in Java Servlets. It allows a servlet to forward a request to another resource (servlet, JSP, or HTML file) on the server or include the response from another resource in its own response. This enables the creation of modular and reusable components in web applications, improving code organization and maintainability.

Answer:

Python is a versatile programming language used in various domains, including:

  • Web development (Django, Flask, Pyramid)
  • Data analysis and data science (Pandas, NumPy, SciPy)
  • Machine learning and artificial intelligence (TensorFlow, PyTorch, scikit-learn)
  • Scientific computing and simulations
  • Automation and scripting
  • Game development (Pygame)
  • Desktop application development (using libraries like Tkinter)
  • Network programming
  • Internet of Things (IoT) projects
  • Web scraping and data extraction

Answer:

MVC (Model View Controller) and MVP (Model View Presenter) are both architectural patterns for designing user interfaces, but they differ in how they handle interaction between components:

MVC MVP
Model manages the data and business logic. Model still manages data and business logic.
View displays the data and interacts with users. View is responsible for displaying data and handling user input.
Controller receives user input and orchestrates communication between Model and View. Presenter acts as an intermediary between Model and View. It processes user input, updates the Model, and updates the View.
The View is often aware of the Model. The View is more passive and doesn’t know much about the Model.

Answer:

The MEAN Stack is a combination of open-source technologies used to build dynamic web applications. The MEAN Stack allows developers to use a consistent language (JavaScript) for both the front-end and back-end development, making the development process smoother.

It consists of:

  1. MongoDB: A NoSQL database that stores data in JSON-like documents.
  2. Express.js: A web application framework for Node.js that simplifies building APIs and handling requests.
  3. Angular.js (now just Angular): A front-end framework for creating dynamic and interactive single-page applications.
  4. Node.js: A runtime environment for executing JavaScript on the server side.

Answer:

An application server is a software framework that provides a runtime environment for running applications. It handles the execution of application logic, managing connections to databases, and often provides various services such as security, transaction management, and messaging. Application servers facilitate the deployment and management of complex business applications.

When a client makes a request, the application server receives the request, processes it by executing the application’s business logic, retrieves data from databases or other services, and then sends the response back to the client.

Answer:

To optimize SQL queries and improve database performance:

  • Use indexes on columns frequently used in WHERE, JOIN, and ORDER BY clauses.
  • Write efficient queries with only the necessary columns and minimal joins.
  • Use EXPLAIN or similar tools to analyze query execution plans.
  • Avoid using SELECT * and fetch only the required columns.
  • Use appropriate data types for columns to save space and enhance performance.
  • Avoid using functions or operations in WHERE clauses that prevent index usage.
  • Batch database operations when possible.
  • Optimize long-running queries and avoid unnecessary subqueries.

Answer:

To address browser compatibility issues:

  • Use modern HTML and CSS features with graceful degradation for older browsers.
  • Test your website on multiple browsers, including Chrome, Firefox, Safari, and Edge.
  • Use CSS frameworks like Bootstrap that provide consistent styling across browsers.
  • Leverage CSS resets or normalization to mitigate browser-specific styling differences.
  • Implement feature detection using libraries like Modernizr to adapt code based on browser capabilities.
  • Use polyfills to provide missing features or functionality in older browsers.
  • Regularly update your code and libraries to stay compatible with evolving browser standards.

Answer:

  • An abstract class can have abstract and non-abstract methods, while an interface can only have abstract methods (prior to Java 8).
  • A class can extend only one abstract class, but it can implement multiple interfaces.
  • Variables in an abstract class can be non-final and non-static, while interface variables are by default static and final.
  • Abstract classes can have constructors, while interfaces cannot.
  • Abstract classes can provide a base implementation for methods, whereas interfaces only declare method signatures.
  • Since Java 8, interfaces can have default and static methods, blurring the distinction somewhat.
  • Abstract classes support public, protected, and private access modifiers for members, while interface members are public by default.

Answer:

Floating elements in CSS can lead to layout issues where subsequent elements don’t behave as expected due to the floated elements not affecting the layout flow. Clearing floats is necessary to ensure proper layout and prevent unexpected behavior. There are a few methods to clear floats:

  • Clearfix Method: : Use a “clearfix” class on the parent element containing floated elements. This class uses the ::after pseudo-element to insert an empty content box that clears the floated elements.
  • Empty Div Method: Place an empty
    element with the clear CSS property after the floated elements within the parent element.
  • Overflow Method: Apply the overflow: auto; or overflow: hidden; CSS property to the parent element containing floated elements. This method triggers a new block formatting context, which clears the floats.

Answer:

In JavaScript, you can share code between files using module systems like CommonJS (used in Node.js) or ES6 Modules (supported in modern browsers). These systems allow you to import and export functionality between different files:

  • CommonJS (Node.js): To share code using CommonJS, you can use the require function to import functionality from another module and use the module.exports or exports object to export functionality from a module.
  • ES6 Modules: With ES6 Modules, you use the import statement to import functionality and the export keyword to export functionality.

Answer:

Host objects and Native objects are terms used to categorize objects in the JavaScript environment:

Host Objects: Native Objects:
Host objects are provided by the environment in which JavaScript runs, such as browsers or Node.js. Native objects are built-in objects provided by the JavaScript language itself.
Examples include objects like window (in the browser), document, and XMLHttpRequest. Examples include objects like String, Array, Object, and Number.
Behavior and features of host objects can vary between different environments. Native objects have consistent behavior across different JavaScript environments.

Answer:

The best way to remove duplicates from an array in ES6 is to use the Set data structure, which only allows unique values. You can convert the array to a Set, and then convert the Set back to an array to get the unique values.

Answer:

Strict Mode is a feature in JavaScript introduced in ECMAScript 5 that enforces a stricter set of rules for writing JavaScript code. It helps to catch common coding mistakes and improve overall code quality. To enable Strict Mode, you simply add the string “use strict”; at the beginning of a script or function. When you enable Strict Mode, it can help catch silent errors like assigning values to undefined variables, using reserved keywords, and other common mistakes that might not throw errors in non-strict mode.

Answer:

Database indexing is a technique used to improve the efficiency of data retrieval operations in a database. Indexes are data structures that store a subset of data from a table in a more compact and optimized form. They work like an index in a book, allowing the database system to quickly locate the desired data without having to scan the entire table.

When you create an index on a column or set of columns, the database system builds a separate data structure that stores the indexed values along with pointers to the corresponding rows in the table. This structure allows the database to perform binary search or other efficient lookup algorithms to quickly find the desired data.

However, indexes come with a trade-off. While they speed up data retrieval, they also consume additional storage space and require maintenance whenever data is inserted, updated, or deleted.

Answer:

Filters in Vue.js are a feature that allows you to format and manipulate text-based data before rendering it in the template. Filters are applied in the template using the {{ expression | filter }} syntax. Filters are particularly useful when you want to display data in a specific format without modifying the actual data in the component’s data object.

Answer:

The inconsistency of the “this” keyword in JavaScript arises from the fact that its value is determined by how a function is called, rather than where it is defined. The value of “this” depends on the context of the function invocation. This can lead to unexpected behavior and bugs, especially in complex codebases or when functions are used in different ways.

The value of “this” can change based on how a function is invoked:

  • In a regular function, “this” refers to the object that the function is called on.
  • In a function defined within an object (method), “this” refers to the object itself.
  • In an event handler, “this” often refers to the DOM element that triggered the event.
  • The value of “this” can be explicitly controlled using functions like call, apply, or bind.

To avoid inconsistencies, it’s important to have a clear understanding of how “this” works in different contexts and to use arrow functions, which have a lexical “this” binding, if needed.

Answer:

A data structure is a way of organizing and storing data in a computer’s memory or storage in a manner that allows efficient access and modification. There are two main types of data structures:

Linear Data Structures:

  • Arrays: A collection of elements, each identified by an index or key.
  • Linked Lists: A sequence of elements, each containing a reference to the next element.
  • Stacks: A collection of elements with Last-In-First-Out (LIFO) access.
  • Queues: A collection of elements with First-In-First-Out (FIFO) access.

Non-Linear Data Structures:

  • Trees: A hierarchical structure with nodes connected by edges.
  • Graphs: A collection of nodes (vertices) connected by edges.
  • Hash Tables: A data structure that stores key-value pairs, allowing fast data retrieval.
  • Heaps: A specialized tree-based structure for priority queue operations.

Answer:

Semantic HTML tags are elements that carry meaning about the content they enclose. They convey information about the type and purpose of the content, making it easier for both browsers and developers to understand the structure and hierarchy of a webpage. Semantic tags provide better accessibility, search engine optimization (SEO), and maintainability.

Using semantic HTML tags has several benefits:

  • Improved Accessibility: Semantic tags help assistive technologies understand the content and provide a better experience for users with disabilities.
  • SEO: Search engines use semantic tags to better understand and index the content of a webpage, which can improve search engine rankings.
  • Readability and Maintainability: Semantic tags make the code more understandable, making it easier for developers to work with and maintain.
  • Future Compatibility: As browsers and technologies evolve, semantic tags are more likely to remain relevant and compatible.