30+ Tirupati Mahima Industries Interview Questions and Answers

Higher-order functions are functions that take one or more functions as arguments or return a function as their result.

• Higher-order functions can be used to create reusable code by abstracting common patterns.

• They enable functional programming paradigms like currying and composition.

• Examples of higher-order functions in JavaScript include map, filter, and reduce.

Development dependencies are needed for development and testing, while regular dependencies are needed for the application to run.

• Development dependencies are used during the development process, such as testing frameworks or build tools.

• Regular dependencies are required for the application to function properly in production.

• Development dependencies are typically listed in the devDependencies section of package.json, while regular dependencies are listed in dependencies.

• Examp...read more

Presentation components are class components that handle rendering, while functional components are simpler and handle stateless rendering.

• Presentation components are also known as container components.

• Functional components are also known as stateless components.

• Presentation components are used for complex UI logic and state management.

• Functional components are used for simple UI logic and stateless rendering.

• Functional components are easier to test and maintain.

• Example of pr...read more

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

• Hoisting applies to both variable and function declarations.

• Variable declarations are hoisted but not their initializations.

• Function declarations are fully hoisted, allowing them to be called before they are declared.

• Hoisting does not apply to variables declared with let or const.

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

Symbols ^ and ~ in package.json represent version ranges for dependencies.

• The symbol ^ represents a range that allows minor version updates.

• The symbol ~ represents a range that allows only patch updates.

• For example, ^1.2.3 allows any version from 1.2.3 to <2.0.0, while ~1.2.3 allows any version from 1.2.3 to <1.3.0.

Component lifecycle in functional components involves useEffect hook for side effects.

• Functional components use useEffect hook to handle side effects like fetching data, subscribing to events, etc.

• useEffect hook can be used to mimic componentDidMount, componentDidUpdate, and componentWillUnmount lifecycle methods.

• useEffect hook takes a callback function as its first argument and an optional array of dependencies as its second argument.

• The callback function inside useEffect ru...read more

var is function scoped, let and const are block scoped.

• var can be redeclared and updated within its scope

• let can be updated but not redeclared within its scope

• const cannot be updated or redeclared once declared

• let and const are not hoisted like var

• const must be initialized during declaration

Redux is a predictable state container for JavaScript apps. It is used to manage application state in a centralized way.

• Use Redux when you have complex state management needs in your application.

• Redux is helpful for large applications with many components that need access to the same state.

• Avoid using Redux for simple applications with minimal state management requirements.

• Consider using React's built-in state management for smaller applications or components.

• Redux can be use...read more

React lifecycle methods are methods that are invoked at different stages of a component's life cycle.

• Some lifecycle methods include componentDidMount, componentDidUpdate, componentWillUnmount, etc.

• In functional components, we can achieve similar functionality using useEffect hook.

• For example, useEffect with an empty dependency array can mimic componentDidMount, while useEffect with dependencies can mimic componentDidUpdate.

404 page can be handled in React routing by creating a Route component with a path of '*' at the end of all other routes.

• Create a Route component with a path of '*' at the end of all other routes in the Switch component.

• Inside the '*' Route component, render a custom 404 page component.

• Use the Switch component to ensure that only one Route is rendered at a time.

Checklist for improving performance of React application

• Use React.memo or PureComponent for optimizing rendering

• Avoid unnecessary re-renders by using shouldComponentUpdate or React.memo

• Use code splitting to load only necessary components

• Optimize state management with libraries like Redux or Context API

• Minimize the use of inline styles and prefer CSS stylesheets for better performance

Git commands for committing, merging code, and resolving merge conflicts

• To commit code: git commit -m 'Commit message'

• To merge code from a branch: git merge branch_name

• To resolve merge conflicts: manually edit the conflicting files, add changes, and then commit the merge

Remove elements from source array present in another array passed to a function

• Loop through elements in source array and check if they exist in the other array

• If an element is found in both arrays, remove it from the source array

Hooks are a feature in React.js that allow developers to use state and other React features in functional components.

• Hooks are functions that let you use React features in functional components

• They allow you to use state and other React features without writing a class

• Hooks provide a way to reuse stateful logic between components

• Some commonly used hooks are useState, useEffect, and useContext

Var is function scoped, let is block scoped. Redux is a predictable state container, Flux is an architecture pattern.

• Var can be redeclared and updated within its scope, let cannot be redeclared but can be updated within its scope

• Redux has a single store for the entire application, while Flux has multiple stores

• Redux uses a unidirectional data flow, while Flux uses a bidirectional data flow

• Redux has middleware for handling side effects, while Flux does not have built-in suppor...read more

Conditional rendering in React allows components to render different elements or components based on certain conditions.

• Conditional rendering is achieved using JavaScript expressions inside JSX.

• Common conditional rendering techniques include using if statements, ternary operators, and logical && operator.

• Example: rendering a component only if a certain condition is met - {condition ? : null}

Props are immutable and passed from parent component, while state is mutable and managed within the component.

• Props are read-only and cannot be modified by the component receiving them.

• State is mutable and can be changed by the component that owns it.

• Props are passed from parent to child components, while state is managed within the component itself.

• Example: Props can be used to pass data from a parent component to a child component, while state can be used to manage form inp...read more

Redeclaration in JavaScript refers to the act of declaring a variable or function multiple times within the same scope.

• Redeclaring a variable using the 'var' keyword will not throw an error but will simply update the value of the variable.

• Redeclaring a variable using the 'let' or 'const' keyword within the same scope will result in a syntax error.

• Redeclaring a function within the same scope will override the previous function definition.

Redux is a predictable state container for JavaScript apps.

• Redux is a state management library commonly used with React.

• It helps in managing the state of the application in a predictable way.

• Redux follows a unidirectional data flow architecture.

• Actions are dispatched to update the state, which is stored in a single immutable state tree.

• Reducers are pure functions that specify how the state should change in response to actions.

The 'any' type in TypeScript is used when the type of a variable is not known during development.

• Use 'any' when working with dynamic data types or when the type cannot be determined at compile time.

• Avoid using 'any' as much as possible to maintain type safety and improve code quality.

• Consider using 'unknown' type instead of 'any' for better type checking and error prevention.

React offers a component-based architecture, virtual DOM for performance optimization, and a strong community support.

• Component-based architecture allows for reusability and easier maintenance of code.

• Virtual DOM helps in improving performance by only updating the necessary parts of the actual DOM.

• React has a strong community support with a vast ecosystem of libraries and tools available.

• React allows for server-side rendering for better SEO performance.

• React Native allows for...read more

useReducer is a React hook that manages state changes through a specified reducer function. useContext is a hook that allows access to a context object.

• useReducer is used for managing complex state logic in React applications.

• It takes in a reducer function and an initial state, and returns the current state and a dispatch function.

• Example: const [state, dispatch] = useReducer(reducer, initialState);

• useContext is used for accessing context values in React components.

• It takes a...read more

Function currying is a technique of transforming a function that takes multiple arguments into a sequence of functions that each take a single argument.

• Currying allows partial application of a function.

• It helps in creating reusable functions.

• Curried functions are composable and can be easily combined to create new functions.

• Currying can be achieved using closures or by using libraries like Lodash or Ramda.

• Example: const add = x => y => x + y; add(2)(3) returns 5.

Closures are functions that have access to variables in their outer scope, even after the outer function has returned.

• Closures are created when a function is defined inside another function.

• The inner function has access to the outer function's variables and parameters.

• Closures can be used to create private variables and methods.

• Closures can also be used to create functions with pre-set arguments.

One way data binding is a unidirectional flow of data from the model to the view in React applications.

• Data flows from the model (or source of truth) to the view, but not vice versa.

• Changes in the model automatically update the view, but changes in the view do not affect the model.

• Helps in maintaining a clear and predictable data flow in React components.

I have used useState, useEffect, useContext, useReducer, and useRef hooks in my projects.

• useState - for managing state in functional components

• useEffect - for handling side effects in functional components

• useContext - for accessing context in functional components

• useReducer - for managing complex state logic in functional components

• useRef - for accessing DOM elements or storing mutable values

useEffect is a hook in React that allows you to perform side effects in functional components.

• It replaces componentDidMount, componentDidUpdate, and componentWillUnmount.

• It takes two arguments: a function that performs the side effect and an array of dependencies.

• The function is called after every render, unless the dependencies haven't changed.

• Common use cases include fetching data, setting up event listeners, and updating the document title.

• Example: useEffect(() => { docume...read more

Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their scope.

• Variables declared with var are hoisted to the top of their scope

• Function declarations are hoisted before variables

• Function expressions are not hoisted

• Hoisting can lead to unexpected behavior and bugs

Redux data flow is a unidirectional flow of data in React applications using a centralized store.

• Actions are dispatched to the store

• Reducers update the state based on the action

• Components subscribe to the store to access the updated state

State is mutable and managed within the component, while props are immutable and passed from parent component.

• State is managed within the component and can be changed using setState() method

• Props are passed from parent component to child component and cannot be changed by the child component

• State is used for internal component data management, while props are used for passing data from parent to child components

Redux middleware is a function that intercepts actions before they reach the reducer.

• Middleware can be used for logging, crash reporting, asynchronous API calls, etc.

• It sits between the action dispatch and the reducer.

• Examples of popular middleware include redux-thunk and redux-saga.

DOM tree is a hierarchical representation of HTML elements in a web page.

• DOM stands for Document Object Model.

• It is a tree-like structure where each node represents an HTML element.

• The DOM tree is created by the browser when a web page is loaded.

• It allows JavaScript to manipulate the content, structure, and style of a web page.

Closures in JavaScript are functions that have access to variables from their outer scope even after the outer function has finished executing.

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

• They help in creating private variables and data encapsulation.

• Closures are created whenever a function is defined within another function.