freeCodeCamp Challenge Guide: Balanced brackets

Guide
1

Balanced brackets

Solutions

### Solution #1 (Click to Show/Hide) 
function isBalanced(str) {
  if (str === "") return true;

  str = str.split("");
  let stack = [];
  for (let i = 0; i < str.length; i++) {
    if (str[i] === "[") {
      stack.push("[");
    } else if (str[i] === "]" && stack[stack.length - 1] === "[") {
      stack.pop();
    }
  }
  return stack.length === 0;
}

Code Explanation

  • Split the input string into individual characters & loop over them.
  • Push every [ into a stack.
  • Check if the item stored on the stack is [ when a ] occurs. This makes it a pair & [ can be removed from the stack.
  • The brackets are balanced if there is no item present in the stack.