Virtusa Consulting Services React Js Frontend Developer Interview Questions and Answers

Iterate through the given string to check if the substring is present.

• Iterate through the given string and check if each character matches the first character of the substring.

• If a match is found, check the subsequent characters to see if they form the substring.

• Return true if the entire substring is found within the given string, otherwise return false.

Traditional functions are defined using the function keyword, while arrow functions are defined using a concise syntax with =>.

• Traditional functions are hoisted, while arrow functions are not.

• Arrow functions do not have their own 'this' keyword, they inherit it from the parent scope.

• Arrow functions are more concise and easier to read compared to traditional functions.

• Traditional functions are better for methods in objects, while arrow functions are better for callbacks or eve...read more

Program to find frequency of letters in a string

• Create an object to store the frequency of each letter

• Loop through the string and increment the count of each letter in the object

• Convert the object into an array of strings with letter and frequency pairs

useState is used to manage state in functional components, while useEffect is used to perform side effects in functional components.

• useState is used to declare state variables in functional components.

• useEffect is used to perform side effects in functional components, such as data fetching, subscriptions, or manually changing the DOM.

• useState does not trigger re-renders, while useEffect can be used to trigger re-renders based on dependencies.

• useState can be used multiple time...read more

Creating a counter in React to increment and decrement a value.

• Create a state variable to store the count value

• Use setState to update the count value

• Render the count value in the component

• Add buttons to increment and decrement the count value

Callback hell is a situation where multiple nested callbacks make the code difficult to read and maintain.

• Occurs when multiple asynchronous operations are nested within each other

• Leads to deeply nested code structure which is hard to understand

• Can be avoided by using Promises, async/await, or modularizing code