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 "leetcode".
• Only the first letter in this word is capital, like "Google".

Given a string word, return true if the usage of capitals in it is right.

Input: word = "USA"
Output: true

Solution

/**
 * @param {string} word
 * @return {boolean}
 */
var detectCapitalUse = function (word) {
  //Case 1: All letters in this word are capitals, like "USA"
  if (word.toUpperCase() === word) return true;
  //Case 2: All letters in this word are not capitals, like "leetcode"
  if (word.toLowerCase() === word) return true;
  //Case 3: Only the first letter in this word is capital, like "Google"
  if (
    word[0].toUpperCase() === word[0] &&
    word.slice(1).toLowerCase() === word.slice(1)
  )
    return true;
  else {
    return false;
  }
};