Cognizant Reactjs Developer Interview Questions, Process, and Tips

Q1. What is closure in javascript?
Ans. 
Closure is a feature in JavaScript that allows a function to access variables in its outer scope.
• A closure is created when a function is defined inside another function.

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

• The outer function's variables and parameters are not accessible from outside the closure.

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

• Example: function outer...read more
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Q2. What are ES6 features?
Ans. 
ES6 features are new additions to JavaScript language syntax and functionality.
• Arrow functions

• Template literals

• Let and const keywords

• Destructuring assignment

• Spread and rest operators

• Classes

• Modules

• Promises

• Default parameters

• Object.assign()

• Symbol data type
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Q1. React basic,event loop, Lazy Loading, Suspense, Javascript basics
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Q2. Create counter application
Ans. 
Counter application using Reactjs
• Create a React component for the counter

• Use state to keep track of the count

• Implement functions to increment and decrement the count

• Display the count on the screen
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Q1. Splice & slice difference
Ans. 
Splice is used to add/remove elements from an array, while slice is used to extract a portion of an array without modifying the original array.
• Splice modifies the original array, while slice does not.

• Splice can add elements, remove elements, or replace elements in an array.

• Slice returns a new array with the selected elements from the original array.

• Example: const arr = [1, 2, 3, 4, 5]; arr.splice(2, 1); // removes elem...read more
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Q2. Coding question | How to reverse string
Ans. 
To reverse a string, iterate through the characters and swap them from start to end.
• Create an empty string to store the reversed result.

• Iterate through the characters of the input string from end to start.

• Append each character to the empty string to reverse the order.

• Return the reversed string.
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Q1. Basics of javascript and react concept.
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Asked about vanilla.js in react interview.