VELOTIO Technologies React Js Frontend Developer Interview Questions and Answers

Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope during compilation.

• Variable declarations are hoisted to the top of their scope but not their initializations.

• Function declarations are fully hoisted, meaning they can be called before they are declared.

• Hoisting can lead to unexpected behavior if not understood properly.

Throttling is a technique used to control the rate at which a function is executed.

• Throttling limits the number of times a function can be called over a specified period of time.

• It helps in optimizing performance by preventing excessive function calls, especially in scenarios like scroll events or API requests.

• Example: Throttling can be used to limit the rate at which a user can resize a window, ensuring smoother perfo...read more

Debouncing is a technique used to limit the number of times a function is called in a short period of time.

• Debouncing is often used in scenarios like search bars where you want to wait for the user to finish typing before making an API call.

• It involves setting a delay before executing a function after the last time it was called.

• Debouncing helps in optimizing performance by reducing unnecessary function calls.

• Example: ...read more

Event coupling is the dependency between different parts of a system based on events.

• Event coupling occurs when one component triggers an event that another component listens for.

• It can lead to tight coupling between components, making the system harder to maintain.

• Reducing event coupling can be achieved by using a centralized event bus or implementing a pub/sub pattern.

• Example: A button click event in a UI component t...read more

Use Set to remove duplicates from array of strings

• Create a Set from the array to automatically remove duplicates

• Convert the Set back to an array to get unique values

• Example: const arr = ['apple', 'banana', 'apple', 'orange']; const uniqueArr = [...new Set(arr)];

Reverse a linked list by changing the direction of pointers

• Create three pointers: prev, current, next

• Iterate through the linked list, updating pointers to reverse the direction

• Return the new head of the reversed linked list

Closure function is a function defined inside another function, with access to the outer function's variables.

• Closure functions have access to the outer function's variables even after the outer function has finished executing.

• They can be used to create private variables and functions in JavaScript.

• Example: function outerFunction() { let outerVar = 'I am outer'; function innerFunction() { console.log(outerVar); } retur...read more