Valid Parentheses

Problem statement

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

1. Open brackets must be closed by the same type of brackets.
2. Open brackets must be closed in the correct order.

Example 1:

Input: s = "()"Output: true

Example 2:

Input: s = "()[]{}"Output: true

Example 3:

Input: s = "(]"Output: false

Constraints:

• 1 <= s.length <= 104
• s consists of parentheses only '()[]{}'.

My solution

/**
 * @param {string} s
 * @return {boolean}
 */
var isValid = function(s) {
    const front = new Set(["(", "{", "["])
    const back = new Map([[")", "("], ["}", "{"], ["]", "["]])
    
    const stack = [];
    
    for (const char of s.split("")) {
        // console.log("char", char)
        if (front.has(char)) {
            stack.push(char)
        } else {
            const last = stack.pop();
            // console.log("last", last)
            if (back.get(char) !== last) {
                return false
            }
        }
    }
    
    return stack.length === 0
};