Vnv Vishwanath & Co Interview Questions and Answers

Aggregation pipeline in MongoDB is a framework for data aggregation operations.

• Pipeline stages are used to process documents in a collection.

• Operators like $match, $group, $project are used in pipeline stages.

• Results can be transformed, sorted, grouped, and filtered using aggregation pipeline.

• Example: db.collection.aggregate([{$match: {field: value}}, {$group: {_id: '$field', count: {$sum: 1}}}, {$sort: {count: -1}}])

SPA stands for Single Page Application. React is a popular JavaScript library for building SPAs.

• SPA is a web application that loads a single HTML page and dynamically updates the page as the user interacts with it.

• React is a JavaScript library for building user interfaces, including SPAs.

• React uses a virtual DOM to efficiently update the UI without reloading the entire page.

• React Router is commonly used with React to handle routing in SPAs.

The question was related to designing a scalable system for handling large amounts of data.

• Focus on distributed systems and scalability

• Consider using technologies like Hadoop, Spark, or Kafka

• Discuss strategies for data partitioning and replication

React DOM is a package that provides DOM-specific methods that can be used to render React components.

• React DOM is used to render React components in the DOM.

• It provides methods like ReactDOM.render() to render components.

• React DOM takes care of updating the DOM to match the React components.

Find and return the duplicate element in an array of strings.

• Iterate through the array and keep track of elements seen so far using a hash set.

• If an element is already in the hash set, return it as the duplicate element.

• Example: ['apple', 'banana', 'apple', 'orange'] should return 'apple' as the duplicate element.