Ernst & Young Front end Developer Interview Questions and Answers

Q1. Fir arrow function This keyword Promises Promise chain Generator function Rest operator Spread operator React hooks Higher order component Redux life cycle Palindrome string code Fibonacci code
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2 moderate DSA questions and a Question on React on Api's to fetch data

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. HTML CSS JS Angular React Questions
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Q1. What are closures with examples ?
Ans. 
Closures are functions that have access to their own scope, as well as the scope in which they were defined.
• Closures allow functions to access variables from their outer function even after the outer function has finished executing.

• Closures are commonly used in event handlers and callbacks.

• Example: function outerFunction() { let outerVar = 'I am outer'; return function innerFunction() { console.log(outerVar); }; }
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Q2. How to get updated content on scroll on e-commerce app?
Ans. 
Use infinite scrolling to fetch new content as user scrolls down the page.
• Implement infinite scrolling to load more products as user scrolls down

• Make AJAX calls to fetch new content from the server

• Update the DOM with the new content dynamically
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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

Q1. Hoisting concept with examples and guess the output
Ans. 
Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope.
• Variable declarations are hoisted but not their initializations.

• Function declarations are fully hoisted.

• Example: console.log(myVar); var myVar = 10; // Output: undefined

• Example: console.log(myFunc()); function myFunc() { return 'Hello!'; } // Output: Hello!
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Q2. Map functionality with a call back function
Ans. 
Using map function to apply a callback function to each element in an array
• Map function is used to iterate over an array and apply a callback function to each element

• The callback function can perform operations on each element and return a new value

• Example: arr.map(item => item * 2) will double each element in the array
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Q3. Copy object, spread operator usage . Deep copy, sallow copy
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Q4. Flexbox vs grid, dom, box model,
Ans. 
Flexbox is best for one-dimensional layouts, Grid is best for two-dimensional layouts, DOM is the structure of a webpage, Box model is the layout of elements.
• Flexbox is best for creating one-dimensional layouts like navigation bars or sidebars.

• Grid is best for creating two-dimensional layouts like grids of images or cards.

• DOM (Document Object Model) is the structure of a webpage, representing the elements as objects.

• Bo...read more
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Q5. React optimization, why React,
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