Problem Solving

Question 1

How do you reverse a string in JavaScript?

Answer 1

javascript
function reverseString(str) {
  return str.split('').reverse().join('');
}

This function splits the string into an array of characters, reverses the array, and joins it back into a string.

Question 2

Write a SQL query to find the second highest salary.

Answer 2

sql
SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees);

This query selects the maximum salary from the employees table that is less than the maximum salary overall.

Question 3

What is the difference between synchronous and asynchronous code?

Answer 3

• Synchronous code runs sequentially and blocks execution.
• Asynchronous code runs in the background and uses callbacks, promises, or async/await.

Synchronous code waits for each operation to complete before moving on, while asynchronous code allows other operations to run while waiting for a response.

Question 4

Write a function to check if a string is a palindrome.

Answer 4

javascript
function isPalindrome(str) {
  return str === str.split('').reverse().join('');
}

This function checks if the string is the same forwards and backwards.