[LeetCode][JavaScript]Valid Parentheses

Valid Parentheses 

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

The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.

https://leetcode.com/problems/valid-parentheses/

 

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水题好愉快。

/**
 * @param {string} s
 * @return {boolean}
 */
var isValid = function(s) {
    var stack = [];
    function brackets(left, right){
        if(left === '(' && right === ')'){
            return true;
        }else if(left === '[' && right === ']'){
            return true;
        }else if(left === '{' && right === '}'){
            return true;
        }
        return false;
    }
    var top = null;
    for(var i in s){
        if(/[\({\[]/.test(s[i])){
            stack.push(s[i]);
        }else{
            if(stack.length > 0){
                top = stack.pop();
                if(!brackets(top, s[i])){
                    return false;
                }
            }else{
                return false;
            }
        }
    }
    
    if(stack.length !== 0){
        return false;
    }  
    return true;
};