isBalanced.js

function isBalanced(str) {
  const stack = str.split('')
  const compare = []
  while(stack.length) {
    //console.log(stack, compare)
    let current = stack.shift();
    if(compare.length == 0) {
      compare.push(current)
    } else {
      if(compare[compare.length - 1] === '(' && current === ')') {
        compare.pop()
      } else {
        compare.push(current)
      }
    }
  }
  return compare.length === 0
}


console.log(isBalanced('()') === true)
console.log(isBalanced('(') === false)
console.log(isBalanced(')') === false)
console.log(isBalanced('()()') === true)
console.log(isBalanced('())(') === false)
console.log(isBalanced(')(') === false)