Ernst & Young Front end Developer Interview Questions and Answers

Q1. How to handle error in javascript
Ans. 
Error handling in JavaScript involves using try-catch blocks, throwing custom errors, and using error objects.
• Use try-catch blocks to catch and handle errors

• Throw custom errors using the throw keyword

• Use error objects like Error, SyntaxError, TypeError, etc. for specific types of errors
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Q2. Explain closure
Ans. 
Closure is a function that retains access to variables from its parent scope even after the parent function has finished executing.
• Closure allows a function to access and manipulate variables from its outer scope.

• It forms a 'closed-over' scope that persists even after the outer function has finished executing.

• Closures are commonly used in event handlers, callbacks, and asynchronous code.

• Example: function outerFunction(...read more
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2 moderate DSA questions and a Question on React on Api's to fetch data

Q1. Tell me about yourself
Ans. 
I am a passionate front end developer with 5 years of experience in creating user-friendly and responsive web applications.
• 5 years of experience in front end development

• Proficient in HTML, CSS, JavaScript, and various front end frameworks

• Strong understanding of UI/UX principles

• Experience in creating responsive web applications

• Passionate about staying updated with the latest web technologies
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Q1. Merge sort time complexity less
Ans. 
Merge sort has a time complexity of O(n log n) in the worst case scenario.
• Merge sort divides the array into two halves, sorts them recursively, and then merges them back together.

• The time complexity of merge sort is O(n log n) in the worst case scenario.

• For example, sorting an array of 8 elements would take 3 recursive calls to merge sort.
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Q2. Palindrome with react js to show on UI
Ans. 
Create a palindrome checker using React JS to display on the UI
• Create a input field for user to enter a string

• Use state to store the input string

• Create a function to check if the input string is a palindrome

• Display the result on the UI
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Javascript question on promise, callbacks, hosting

Basic angular questions like-lazy loading, == === operator etc

Q1. Map function , hashmap
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Q1. JavaScript Related Questions
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Q2. ReactJs Related Questions
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Q1. Reactjs Use Effects and UseRef
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Q2. JavaScript Closures,Map,CallBack
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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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Javascript array questions like palindrom and others with aptitude

Q1. Skill related technical questions
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Q2. How to share data in components react
Ans. 
Data can be shared between components in React using props, context, or state management libraries like Redux.
• Use props to pass data from parent to child components

• Use context to share data across multiple components without passing props manually

• Use state management libraries like Redux to manage global state and share data between components
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Q3. Prop drilling explain in react
Ans. 
Prop drilling is the process of passing data through multiple levels of components in React.
• Prop drilling occurs when a component needs to pass data to a deeply nested child component.

• It can lead to code that is hard to maintain and understand.

• One way to avoid prop drilling is by using Context API or Redux for state management.
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Q4. Redux flow explain
Ans. 
Redux is a predictable state container for JavaScript apps.
• Redux stores the entire state of an application in a single immutable object.

• State changes are made by dispatching actions, which are plain JavaScript objects.

• Reducers specify how the application's state changes in response to actions.

• Redux flow: Action -> Reducer -> Store -> View
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Q1. Previous project discussion
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