Top 10 JavaScript Interview Problems and Solutions You Must Prepare in 2024

Top 10 JavaScript Interview Problems and Solutions You Must Prepare in 2024

1. Write a function that reverses a string.
2. Write a function that checks if a given string is a palindrome.
3. Write a function to calculate the factorial of a given number.
4. Write a function to generate the Fibonacci sequence up to a given number.
5. Write a function to sort an array of numbers.
6. Write a function to find the first duplicate element in an array.
7. Write a function to perform binary search on a sorted array.
8. Given an object, write a function to remove a property by key.
9. Write a function to deep clone an object.
10. Write an asynchronous function that fetches data from an API using Promises and Async/Await.

1. Write a function that reverses a string.

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

2. Write a function that checks if a given string is a palindrome.

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

3. Write a function to calculate the factorial of a given number.

function factorial(n) {
    if (n === 0 || n === 1) return 1;
    return n * factorial(n - 1);
}

4. Write a function to generate the Fibonacci sequence up to a given number.

function fibonacci(n) {
    const sequence = [0, 1];
    for (let i = 2; i <= n; i++) {
        sequence[i] = sequence[i - 1] + sequence[i - 2];
    }
    return sequence;
}

5. Write a function to sort an array of numbers.

function sortArray(arr) {
    return arr.slice().sort((a, b) => a - b);
}

6. Write a function to find the first duplicate element in an array.

function findDuplicate(arr) {
    const set = new Set();
    for (const num of arr) {
        if (set.has(num)) {
            return num;
        }
        set.add(num);
    }
    return undefined;
}

7. Write a function to perform binary search on a sorted array.

function binarySearch(arr, target) {
    let low = 0;
    let high = arr.length - 1;
    while (low <= high) {
        const mid = Math.floor((low + high) / 2);
        if (arr[mid] === target) return mid;
        if (arr[mid] < target) low = mid + 1;
        else high = mid - 1;
    }
    return -1;
}

8. Given an object, write a function to remove a property by key.

function removeProperty(obj, key) {
    delete obj[key];
}

9. Write a function to deep clone an object.

function deepClone(obj) {
    return JSON.parse(JSON.stringify(obj));
}

10. Write an asynchronous function that fetches data from an API using Promises and Async/Await.

async function fetchData(url) {
    const response = await fetch(url);
    const data = await response.json();
    return data;
}

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