Vizlitics Technologies Interview Questions and Answers

Document Object Model (DOM) is a programming interface for web documents.

• DOM is a tree-like structure that represents the HTML or XML document.

• It allows developers to manipulate the content and structure of a web page using programming languages like JavaScript.

• DOM provides a set of methods and properties to access and modify the elements of a web page.

• Changes made to the DOM are reflected in the web page in real-time.

• DOM can be used to create dynamic web pages and web applic...read more

ACID property ensures database transactions are reliable and consistent.

• ACID stands for Atomicity, Consistency, Isolation, and Durability.

• Atomicity ensures that a transaction is treated as a single, indivisible unit.

• Consistency ensures that a transaction brings the database from one valid state to another.

• Isolation ensures that concurrent transactions do not interfere with each other.

• Durability ensures that once a transaction is committed, it will remain so even in the face o...read more

Normalization is the process of organizing data in a database to reduce redundancy and dependency.

• Normalization helps to eliminate data redundancy and inconsistencies.

• It involves breaking down a table into smaller tables and defining relationships between them.

• Normalization is achieved through a series of normal forms, such as first normal form (1NF), second normal form (2NF), and so on.

• Normalization ensures data consistency and improves database performance.

• Example: A custom...read more

Multilevel inheritance is a concept in object-oriented programming where a class inherits properties and methods from another class, which in turn inherits from another class.

• Multilevel inheritance involves creating a hierarchy of classes, where each class inherits from the class above it.

• The derived class inherits the properties and methods of the base class, and can also add its own unique properties and methods.

• This type of inheritance allows for code reusability and promo...read more

Interface defines only method signatures while abstract class can have method implementations.

• Interface cannot have constructors while abstract class can.

• A class can implement multiple interfaces but can inherit only one abstract class.

• Abstract class can have non-abstract methods while interface cannot.

• Abstract class can have instance variables while interface cannot.

• Example of interface: Runnable interface in Java.

• Example of abstract class: HttpServlet class in Java Servlet ...read more

The data structure used to reverse an array is a stack.

• A stack data structure can be used to reverse an array by pushing each element onto the stack and then popping them off in reverse order.

• Example: If we have an array of strings ['apple', 'banana', 'cherry'], we can reverse it using a stack to get ['cherry', 'banana', 'apple'].

To upload files in a Node.js application, you can use the 'multer' middleware package.

• Install 'multer' package using npm

• Set up multer middleware in your Node.js application

• Create a route in your application to handle file uploads

• Use 'multer' to process and save uploaded files to a specified destination