BT Group Software Engineer Interview Questions and Answers

JavaScript prototype sorting function for arrays of strings

• Use the Array.prototype.sort() method to sort an array of strings

• Pass a compare function to specify the sorting order

• Example: ['banana', 'apple', 'cherry'].sort((a, b) => a.localeCompare(b))

Creating a Promise polyfill from scratch involves implementing the Promise API using callbacks and handling asynchronous operations.

• Understand the Promise API and its methods (resolve, reject, then, catch)

• Implement a constructor function that takes an executor function as an argument

• Handle asynchronous operations using callbacks and setTimeout

• Implement the then and catch methods to handle success and error cases respec

Session management is the process of securely managing user sessions in web applications.

• Use cookies or tokens to track user sessions

• Implement session timeout to prevent unauthorized access

• Store session data securely on the server side

• Use HTTPS to encrypt session data during transmission

React is faster than other frameworks due to its virtual DOM, efficient diffing algorithm, and use of server-side rendering.

• React uses a virtual DOM which allows it to update only the necessary components instead of re-rendering the entire page.

• React's efficient diffing algorithm compares the virtual DOM with the actual DOM to minimize updates and improve performance.

• React supports server-side rendering, which can impr...read more