https://leetcode.com/problems/goat-latin/

goatLatin.js

/**
 * @param {string} S
 * @return {string}
 */

const v = 'aeiouAEIOU';

var toGoatLatin = function(S) {
    return S.split(' ')
    .map((w, i) => (v.indexOf(w[0]) >= 0 ? w : (w.slice(1) + w[0])) + 'ma' + 'a'.repeat(i+1))
    .join(' ');
};