LeetCode: Merge Strings Alternately Solution

1/**
2 * @param {string} word1
3 * @param {string} word2
4 * @return {string}
5 */
6var mergeAlternately = function (word1, word2) {
7  word1 = word1.split("")
8  word2 = word2.split("")
9  let res = ""
10  while (word1.length && word2.length) {
11    res += word1.shift() + word2.shift()
12  }
13  if (word1.length) res += word1.join("")
14  if (word2.length) res += word2.join("")
15  return res
16}