LeetCode - Reverse Only Letters

Given a string s, reverse the string according to the following rules:

All the characters that are not English letters remain in the same position.
All the English letters (lowercase or uppercase) should be reversed.
Return s after reversing it.

Example 1:

Input: s = "ab-cd"
Output: "dc-ba"
Example 2:

Input: s = "a-bC-dEf-ghIj"
Output: "j-Ih-gfE-dCba"
Example 3:

Input: s = "Test1ng-Leet=code-Q!"
Output: "Qedo1ct-eeLg=ntse-T!"

Constraints:

1 <= s.length <= 100
s consists of characters with ASCII values in the range [33, 122].
s does not contain '\"' or '\'.

1. 정규표현식을 이용해 문자인경우 stack 에 보관하고, 해당 공간을 빈문자로 대체한다.
2. 이후 반복문을 돌며 빈문자가 있는 공간에 stack 원소들을 하나씩 꺼내어 채우도록 한다.

/**
 * @param {string} s
 * @return {string}
 */
var reverseOnlyLetters = function(s) {
    let queue = []
    const pattern = /[a-zA-Z]/
    s = s.split('')
    
    for (let i=0; i<s.length; i++) {
        if (pattern.test(s[i]) == true) {
            queue.push(s[i])
            s[i] = ''
        }
    }
    
    for (let i=0; i<s.length; i++) {
        if (s[i] == '') {
            s[i] = queue.pop()
        }
    }
    
    return s.join('')
};