Happiest Minds Technologies Senior Software Engineer Interview Questions and Answers

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.

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 rende...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 has ...read more

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

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 scalab...read more

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 and m...read more