isOpposite.js

/*

Give you two strings: s1 and s2. If they are opposite, return true; otherwise, return false. Note: The result should be a boolean value, instead of a string.

The opposite means: All letters of the two strings are the same, but the case is opposite. you can assume that the string only contains letters or it's a empty string. Also take note of the edge case - if both strings are empty then you should return false/False.

first write a condition if s1 || s2 === '' return false
I have to loop over both parameters
then write a condition if s1 === s2 return false else return true



*/

const isOpposite = (s1, s2) => {
  if (s1 === s2 || s1.lowerCase() != s2.lowerCase()) {
    return false;
  }

  for (let i = 0; i < s1.length; i++) {
    if (s1.charAt(i) === s2.charAt(i)) {
      return false;
    }
  }
  return true;
};