Judge whether the usage of capitals in it is right or not

This problem was asked by Google.

Given a word, you need to judge whether the usage of capitals in it is right or not.

We define the usage of capitals in a word to be right when one of the following cases holds:

• All letters in this word are capitals, like "USA".
• All letters in this word are not capitals, like "dailyfrontendproblem".
• Only the first letter in this word is capital if it has more than one letter, like "Google".
• Otherwise, we define that this word doesn't use capitals in a right way.

Example

const detectCapitalUse = word => {

};

console.log(detectCapitalUse("USA")) // true
console.log(detectCapitalUse("FlaG")) // true
Note: The input will be a non-empty word consisting of uppercase and lowercase latin letters.

Solution

const detectCapitalUse = (word) => {
  if (word.toUpperCase() === word) return true;
  else if (word.toLowerCase() === word) return true;
  else {
    return (
      word[0].toUpperCase() === word[0] &&
      word.slice(1).toLowerCase() === word.slice(1)
    );
  }
};