Happiest Minds Technologies Senior Software Engineer Interview Questions and Answers

Microservices are a software architecture style that structures an application as a collection of loosely coupled services.

• Microservices are independently deployable services that communicate over a network.

• Each microservice is responsible for a specific business capability, e.g., user authentication.

• Microservices can be developed in different programming languages, allowing for technology diversity.

• They enhance s...read more

Data types in JavaScript include number, string, boolean, object, function, undefined, and null.

• Number - represents numeric data, e.g. 10, 3.14

• String - represents textual data, e.g. 'hello', '123'

• Boolean - represents true or false values, e.g. true, false

• Object - represents complex data structures, e.g. { key: 'value' }

• Function - represents executable code, e.g. function() { }

• Undefined - represents a variable that...read more

Virtual DOM is a lightweight copy of the actual DOM used for efficient updates in web development.

• Virtual DOM is a concept used in frameworks like React to improve performance by minimizing actual DOM manipulations.

• When changes are made to the virtual DOM, a comparison is done with the actual DOM to determine the minimal updates needed.

• This approach reduces the number of costly DOM operations, resulting in faster ...read more

Closures are functions that have access to variables from their containing scope even after the scope has closed.

• Closures allow functions to access variables from their outer function even after the outer function has finished executing.

• They are commonly used in event handlers, callbacks, and asynchronous programming.

• Closures help in maintaining state in functional programming.

React code for a simple counter

• Create a functional component for the counter

• Use useState hook to manage the count state

• Render the count value and buttons to increment and decrement the count

I manage load and system interactions using async programming, load balancing, and efficient resource management.

• Utilize asynchronous programming to handle multiple requests without blocking, e.g., using async/await in JavaScript.

• Implement load balancing techniques, such as round-robin or least connections, to distribute traffic evenly across servers.

• Use message queues (e.g., RabbitMQ, Kafka) to decouple services ...read more

Design patterns are reusable solutions to common software problems. One example is the Singleton pattern.

• Creational patterns: Singleton, Factory, Abstract Factory, Builder

• Structural patterns: Adapter, Bridge, Composite, Decorator, Facade, Flyweight, Proxy

• Behavioral patterns: Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method, Visitor

• Singleton patt...read more

The number of columns that can be created in a table depends on the database management system being used.

• The limit varies depending on the DBMS

• For MySQL, the limit is 4096 columns per table

• For Oracle, the limit is 1000 columns per table

• The number of columns can also be limited by the available memory and disk space