Parenthesis/Brackets Matching using Stack algorithm (Javascript)

matchinBrackets.js

function matchParenthesis(str){
  const stack = []

  const opening = /(\(|\{|\[)/
  const closing = /(\)|\}|\])/

  if(!str || !str.length) return undefined
  

  for(let i = 0; i  < str.length; i++){
    let letter = str.charAt(i)

    
    if(letter.match(opening)){
      stack.push(letter)
    } else if(letter.match(closing)){
      if(stack[stack.length -1] === '('){
        stack.pop()
      } else {
        return false
      }
    } else if(!letter.match(opening) || !letter.match(closing)){
      return false
    }

  }
  
  return stack.length === 0
}

console.log(matchParenthesis("9"))
console.log(matchParenthesis("((()))"))
console.log(matchParenthesis(")"))
console.log(matchParenthesis("("))
console.log(matchParenthesis("()()"))
console.log(matchParenthesis(")("))
console.log(matchParenthesis("()))(("))
console.log(matchParenthesis("((()()))"))