1-100/0020-valid-parentheses/main.js

/**
 * @param {string} s
 * @return {boolean}
 */
 var isValid = function (s) {
  if(s.length%2===1){
      return false;
  }
  const stack = [];
  for (let i = 0; i < s.length; i++) {
      const c = s[i];
      if (c === '(' || c === '[' || c === '{') {
          stack.push(c);
      } else {
          const t = stack[stack.length - 1];
          if (
              (t === '(' && c === ')') ||
              (t === '[' && c === ']') ||
              (t === '{' && c === '}')
          ) {
              stack.pop();
          } else {
              return false;
          }
      }
  }
  return stack.length === 0;
};