HDFC Bank Interview Questions and Answers

Optimizing Angular app performance and security with router components and services

• Use lazy loading to improve performance

• Implement caching for frequently accessed data

• Use Angular Universal for server-side rendering

• Implement HTTPS and secure authentication for security

• Use guards and interceptors to protect routes and prevent unauthorized access

To make a class immutable, we need to ensure that its state cannot be modified after creation.

• Make all fields private and final

• Do not provide any setters

• If mutable objects are used, return copies instead of references

• Ensure that any methods that modify state return a new instance instead of modifying the existing one

Hoisting in JavaScript is a behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase.

• Variable declarations are hoisted to the top of their scope, but not their initializations.

• Function declarations are fully hoisted, including their definitions.

• Hoisting can lead to unexpected behavior if not understood properly.

React life cycle methods are functions that are called at different stages of a component's life cycle.

• There are three phases of a component's life cycle: Mounting, Updating, and Unmounting.

• Mounting phase includes constructor(), getDerivedStateFromProps(), render(), and componentDidMount() methods.

• Updating phase includes getDerivedStateFromProps(), shouldComponentUpdate(), render(), getSnapshotBeforeUpdate(), and componentDidUpdate() methods.

• Unmounting phase includes componen...read more

A promise is an object representing the eventual completion or failure of an asynchronous operation. A closure is a function defined within another function that has access to its parent function's scope.

• Promise is used to handle asynchronous operations in JavaScript.

• Promises can be in one of three states: pending, fulfilled, or rejected.

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

• Closures are c...read more

Functional overloading involves multiple functions with the same name but different parameters, while function overriding involves a subclass providing a specific implementation for a method in its superclass.

• Functional overloading allows multiple functions with the same name but different parameters.

• Function overriding occurs in inheritance when a subclass provides a specific implementation for a method in its superclass.

• In functional overloading, the compiler determines whi...read more

Design patterns are reusable solutions to common problems in software design.

• Design patterns help in creating maintainable, scalable, and efficient code.

• Some common design patterns include Singleton, Factory, Observer, and Strategy.

• Design patterns can be categorized into three main groups: creational, structural, and behavioral.

Memoization is a technique used in computer science to store the results of expensive function calls and return the cached result when the same inputs occur again.

• Memoization helps in improving the performance of a program by reducing redundant calculations.

• It is commonly used in dynamic programming to optimize recursive algorithms.

• Example: Fibonacci sequence calculation can be optimized using memoization to store previously calculated values.