5 Javascript coding interview questions - Part 1

Question 1: Reverse a String
Write a function that takes a string as input and returns its reverse.

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

// Test
console.log(reverseString('hello')); // Output: "olleh"

Question 2: Check for Palindrome
Write a function that checks if a given string is a palindrome (reads the same forwards and backward).

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

// Test
console.log(isPalindrome('racecar')); // Output: true
console.log(isPalindrome('hello'));   // Output: false

Question 3: Find the First Non-Repeated Character
Write a function that takes a string as input and returns the first non-repeated character in the string.

function firstNonRepeatedChar(str) {
  const charCount = {};

  for (const char of str) {
    charCount[char] = (charCount[char] || 0) + 1;
  }

  for (const char of str) {
    if (charCount[char] === 1) {
      return char;
    }
  }

  return null; // If all characters are repeated
}

// Test
console.log(firstNonRepeatedChar('abacdbe')); // Output: "c"

Question 4: FizzBuzz
Write a function that prints the numbers from 1 to n. For multiples of 3, print "Fizz" instead of the number. For multiples of 5, print "Buzz" instead of the number. For numbers that are multiples of both 3 and 5, print "FizzBuzz".

function fizzBuzz(n) {
  for (let i = 1; i <= n; i++) {
    let output = '';
    if (i % 3 === 0) {
      output += 'Fizz';
    }
    if (i % 5 === 0) {
      output += 'Buzz';
    }
    console.log(output || i);
  }
}

// Test
fizzBuzz(15); // Output: 1, 2, "Fizz", 4, "Buzz", "Fizz", 7, 8, "Fizz", "Buzz", 11, "Fizz", 13, 14, "FizzBuzz"

Question 5: Remove Duplicates from an Array
Write a function that takes an array as input and returns a new array with duplicates removed.

function removeDuplicates(arr) {
  return [...new Set(arr)];
}

// Test
console.log(removeDuplicates([1, 2, 2, 3, 4, 4, 5])); // Output: [1, 2, 3, 4, 5]

These are just a few examples of JavaScript coding interview questions. Remember to practice and understand the concepts thoroughly to perform well in technical interviews.

Javascript coding interview questions part 2