Function to know if the given string is balanced or not

balance_string.js

/**
 * PROBLEM:
 * Create a function that receives a string like "[[[]]]" or "[][]][" and returns true if the string is balanced 
 * or false if the string isn't (to be balanced the string must have the same number of opening and closing brackets 
 * and they must be in the correct order). For example the first given string must return true and the second one must 
 * return false.
 */
const isStringBalanced = string => {
  return !string.split('').reduce((previous, char) => {
    if (previous < 0) return previous;
    if (char === '[') return ++previous;
    if (char === ']') return --previous;
    return previous;
  }, 0);
};

console.log(isStringBalanced('[[[]]]'));
console.log(isStringBalanced('[][]]['));