var isValid = function(s) { let chars = { "(": ")", "{": "}", "[": "]" }; let pickStack = s.split(""); let pushStack = []; while (pickStack.length > 0) { let char = pickStack.pop(); if (char == "(" || char == "{" || char == "[") { if (pushStack.length == 0) { return false; } let pushedChar = pushStack.pop(); if (pushedChar != chars[char]) { return false; } } else { pushStack.push(char); } } if (pushStack.length > 0) { return false; } return true; };