leetcode：20 有效的括号

/**
 * @param {string} s
 * @return {boolean}
 */
var isValid = function(s) {
    let s1=s;
    if(s.length%2!=0)
    {
        return false;
    }
    while(s.length!=0)
    {
        s=s.replace("{}","");
        s=s.replace("[]","");
        s=s.replace("()","");
        if(s==s1)
        {
            return false;
        }
        s1=s
    }
    return true;
};

 s=s.replace("{}","");
 s=s.replace("[]","");
 s=s.replace("()","");

if(s==s1)
        {
            return false;
        }

 s1=s

  let s1=s;