JavaScript coding Interview Questions and Answers — Part 1

• Write a JavaScript program to find the maximum number in an array.
• Write a JavaScript function to check if a given string is a palindrome (reads the same forwards and backwards).
• Write a JavaScript program to reverse a given string.

Q) Write a JavaScript program to find the maximum number in an array.

Ans:

function findMax(arr) {
    if (arr.length === 0) {
        return "Array is empty";
    }

    let max = arr[0];
    for (let i = 1; i < arr.length; i++) {
        if (arr[i] > max) {
            max = arr[i];
        }
    }
    return max;
}

// Example usage:
const numbers = [10, 5, 20, 8, 15];
const maxNumber = findMax(numbers);
console.log("The maximum number in the array is:", maxNumber);

Q) Write a JavaScript function to check if a given string is a palindrome (reads the same forwards and backwards).

Ans:

function isPalindrome(str) {
    // Remove non-alphanumeric characters and convert to lowercase
    const cleanStr = str.toLowerCase().replace(/[^a-z0-9]/g, '');

    // Compare the original string with its reverse
    return cleanStr === cleanStr.split('').reverse().join('');
}

// Example usage:
const string1 = "radar";
const string2 = "hello";

console.log(`"${string1}" is a palindrome:`, isPalindrome(string1)); // true
console.log(`"${string2}" is a palindrome:`, isPalindrome(string2)); // false

Q) Write a JavaScript program to reverse a given string.

Ans:

function reverseString(str) {
    let reversed = '';
    for (let i = str.length - 1; i >= 0; i--) {
        reversed += str[i];
    }
    return reversed;
}

// Example usage:
const originalString = "hello";
const reversedString = reverseString(originalString);
console.log("Original string:", originalString);
console.log("Reversed string:", reversedString);