index.js

/**
 * problem 01
 * 
 * add(num)
 * 
 * @param {number} nums
 * @returns {number}
 */

function add(num) {
    let temp = 0, tempNum = num;
    if(tempNum>9){
        while(tempNum>0){
            temp += tempNum % 10;
            tempNum = parseInt(tempNum / 10);
        }
        return add(temp)
    }
    return tempNum
}

console.log(add(38))
console.log(add(0))


/**
 * problem 02
 * 
 * hasDuplicate(nums)
 * 
 * @param {Array} nums 
 * @returns {boolean}
 */
function hasDuplicate(nums) {
    const maps = []

    for(let i=0; i<nums.length; i++){
        if(maps.includes(nums[i])){
            return true
        }
        maps.push(nums[i])
    }
    return false
}

console.log(hasDuplicate([1,2,3,1]))
console.log(hasDuplicate([1,2,3,4]))
console.log(hasDuplicate([1,1,1,3,3,4,3,2,4,2]))


/**
 * problem 03
 * 
 * reverseVowels(str)
 * 
 * @param {string} str
 * @returns {string}
 */
function reverseVowels(str) {
    let tempStr = str, strArr = [], vowels = ['a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'], count = 0;

    for(let i=0; i<str.length; i++){
        if(vowels.includes(str[i])){
            strArr.push(str[i])
        }
    }

    for(let i=0; i<str.length; i++){
        if(vowels.includes(str[i])){
            tempStr = tempStr.slice(0, i) + strArr[strArr.length - ++count] + tempStr.slice(i+1, tempStr.length)
        }
    }
    return tempStr
}

console.log(reverseVowels("hello") == 'holle')
console.log(reverseVowels("algorithm") == 'ilgorathm')
console.log(reverseVowels("aA") == 'Aa')