IT4T Solutions Front end Developer Interview Questions and Answers for Experienced

Q1. Explain about react js?
Ans. 
React JS is a JavaScript library for building user interfaces.
• React is component-based, allowing for reusable UI elements.

• Uses a virtual DOM for efficient updates to the actual DOM.

• Supports server-side rendering for improved performance.

• Uses JSX syntax to write HTML within JavaScript code.

• State management is handled using props and state.
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Q2. Explain about angular?
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Angular is a popular front-end framework developed by Google for building dynamic web applications.
• Angular is based on TypeScript, a superset of JavaScript.

• It uses a component-based architecture for building reusable UI components.

• Angular provides features like data binding, dependency injection, and routing.

• It has a powerful CLI for scaffolding and managing projects.

• Angular has a large ecosystem of libraries and tools
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Q1. Let var const in JavaScript
Ans. 
var and const are used to declare variables in JavaScript, with var being mutable and const being immutable.
• var is used to declare variables that can be reassigned and updated

• const is used to declare variables that cannot be reassigned or updated

• let is another keyword used for declaring variables, similar to var but with block scope
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Q2. Error boundary and how to handle
Ans. 
Error boundary is a React component that catches JavaScript errors anywhere in a component tree and logs those errors.
• Error boundaries are React components that catch JavaScript errors in their child component tree.

• They are used to prevent the entire UI from crashing due to a single error.

• Error boundaries work like a JavaScript catch {} block, but for components.

• They are defined using componentDidCatch lifecycle method
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Q3. Event.bind and event.property
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Q4. Use of never in typescript
Ans. 
The 'never' type in TypeScript represents a value that will never occur.
• Used to indicate that a function will not return a value

• Commonly used in union types to exclude certain values

• Helps catch potential errors at compile time
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Q5. What hooks you have used
Ans. 
I have used React hooks such as useState, useEffect, useContext, and useRef in my projects.
• useState

• useEffect

• useContext

• useRef
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Q6. What is difference between use reducer and use state
Ans. 
useReducer is preferred for managing complex state logic, while useState is simpler for basic state management.
• useReducer is more suitable for managing complex state logic and multiple state values

• useState is simpler and more straightforward for basic state management with a single value

• useReducer allows for more organized and centralized state updates through actions and reducers

• useState is commonly used for simple co
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Q7. Why we use state and props
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Q8. How you will pass data from parent to child
Ans. 
Data can be passed from parent to child components in React using props.
• Pass data as props from parent component to child component

• Use state management libraries like Redux or Context API for complex data sharing

• Use callback functions to pass data from child to parent components
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Q9. Write your own custom hook
Ans. 
Custom hook to fetch data from an API
• Create a function that uses the useState and useEffect hooks

• Use the fetch API to make a request to the desired endpoint

• Return the fetched data and loading state in an array
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Q10. Explain map filter and reduce functions
Ans. 
Map, filter, and reduce are higher-order functions in JavaScript used to manipulate arrays.
• Map: Transforms each element in an array and returns a new array with the transformed elements.

• Example: [1, 2, 3].map(num => num * 2) returns [2, 4, 6].

• Filter: Returns a new array with elements that pass a certain condition.

• Example: [1, 2, 3].filter(num => num > 1) returns [2, 3].

• Reduce: Applies a function against an accumulator ...read more
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Q11. How you can clone an object
Ans. 
To clone an object in JavaScript, you can use the spread operator or Object.assign() method.
• Use the spread operator to create a shallow copy of an object: const clonedObj = { ...originalObj };

• Use Object.assign() method to create a shallow copy of an object: const clonedObj = Object.assign({}, originalObj);

• For deep cloning, you can use libraries like Lodash or write a custom function to recursively clone nested objects.
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Q12. What are the three stages of event propagation and how to handle it
Ans. 
Event propagation consists of three stages: capturing, target, and bubbling.
• Capturing phase: Events are captured from the outermost element to the target element.

• Target phase: Event reaches the target element where the event originated.

• Bubbling phase: Events bubble up from the target element to the outermost element.
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Q13. How to handle errors in your react application
Ans. 
Errors in a React application can be handled by using error boundaries, try-catch blocks, and displaying error messages to users.
• Use error boundaries to catch errors in components and display a fallback UI

• Wrap code that may throw errors in try-catch blocks to handle exceptions

• Use libraries like React Error Boundary to easily implement error handling

• Display error messages to users to inform them about the issue and poss
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Q14. Write code to call fake api and display the title where category is “some category “
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Q1. Javascipt question
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Q2. Promises, filter, map, What is single page , mulitple page application, opened google page by search for one product in that using console filter it only for sony products only
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Q3. What is DOM, what is the use of that
Ans. 
DOM stands for Document Object Model, it is a programming interface for web documents. It represents the structure of a document as a tree of objects.
• DOM is used to interact with HTML and XML documents in a structured way

• It allows developers to manipulate the content, structure, and style of a website dynamically

• DOM provides methods and properties to access and modify elements on a web page

• Example: document.getElementB...read more
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Q4. What is the output if u type document in console
Ans. 
The output will display the document object in the console.
• Typing 'document' in the console will return the document object, which represents the current HTML document.

• The document object provides access to the content and structure of the webpage, allowing manipulation of elements and properties.
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Q1. How to handle form validation?
Ans. 
Form validation can be handled using client-side and server-side validation techniques.
• Use HTML5 form validation attributes like required, pattern, min, max, etc.

• Implement client-side validation using JavaScript to provide instant feedback to users.

• Perform server-side validation to ensure data integrity and security.

• Display error messages next to the input fields for better user experience.

• Use a combination of front-en...read more
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Q2. Explain the concept of redux-toolkit
Ans. 
Redux Toolkit is an official, opinionated, batteries-included toolset for efficient Redux development.
• Redux Toolkit simplifies Redux code by providing a set of tools and best practices

• It includes utilities like createSlice, createReducer, configureStore, and createAsyncThunk

• Helps in writing concise and readable Redux code with less boilerplate

• Encourages the use of Immer for writing immutable updates in a more intuitive
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Q1. What is AOT And JIT How angular different from react Route guard
Ans. 
AOT (Ahead-of-Time) and JIT (Just-in-Time) are compilation techniques used in Angular. Angular and React differ in their architecture and data binding approach. Route guards in Angular are used to control access to routes.
• AOT compilation in Angular converts TypeScript code into efficient JavaScript code during the build process, resulting in faster rendering and smaller bundle sizes.

• JIT compilation in Angular compiles ...read more
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Q2. How angular application build
Ans. 
Angular applications are built using the Angular CLI, which provides a command-line interface for creating, building, and serving Angular projects.
• Angular applications are built using the Angular CLI (Command Line Interface)

• The Angular CLI provides commands for creating new projects, generating components, services, modules, etc.

• To build an Angular application, you can use the 'ng build' command which compiles the appl
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Q3. Project discussion
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Q1. Angular lifecycle hooks
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Q2. JS interview questions
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Recurrsion tree implementation with angular

Given time aptitude must be cleared

2 codings for 1 hour

Q1. 1. Difference between client-side and server side scripting? 2. What is destructuring? 3. What is HOC? 4. Write code to combine nested array 5. Write code to count the number of vowels in a string
Ans. 
1. Client-side scripting runs on the user's browser, while server-side scripting runs on the server. 2. Destructuring is a way to extract values from objects and arrays. 3. HOC stands for Higher Order Component in React. 4. Combining nested arrays involves flattening them into a single array. 5. Counting vowels in a string involves iterating through the characters and checking if they are vowels.
• Client-side scripting e...read more
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