Ernst & Young Front end Developer Interview Questions and Answers

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. 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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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
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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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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. HTML CSS JS Angular React Questions
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Basic angular questions like-lazy loading, == === operator etc

Q1. Map function , hashmap
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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. 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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