Solution to the Valid Parentheses challenge from LeetCode

valid-parentheses-solution.js

/**
 * Author: Maxim Orlov <hello@maximorlov.com>
 * Website: https://maximorlov.com
 *
 * @param {string} s
 * @return {boolean}
 */
const OPEN_PARENS = ['(', '{', '['];

function isValid(s) {  
  const openedParens = [];
  
  for (const char of s) {
    if (!openedParens.length) {
      if (!OPEN_PARENS.includes(char)) {
        return false;
      }
      
      openedParens.push(char);
    } else {
      if (OPEN_PARENS.includes(char)) {
        openedParens.push(char);
      } else {
        const openedParen = openedParens.at(-1);
        if (openedParen === '(' && char !== ')') {
          return false;
        }
        
        if (openedParen === '{' && char !== '}') {
          return false;
        }
        
        if (openedParen === '[' && char !== ']') {
          return false;
        }
        
        openedParens.pop();
      }
    }
  }

  return !openedParens.length;
};

console.log(isValid('()'))
console.log(isValid('()[]{}'))
console.log(isValid('(]'))
console.log(isValid('({{[)}})'))