String-Transformer.js

/*

Given a string, return a new string that has transformed based on the input:

Change case of every character, ie. lower case to upper case, upper case to lower case.
Reverse the order of words from the input.
Note: You will have to handle multiple spaces, and leading/trailing spaces.

For example:

"Example Input" ==> "iNPUT eXAMPLE"
You may assume the input only contain English alphabet and spaces.
*/

function stringTransformer(str) {
  return str
    .split(' ')
    .reverse()
    .join(' ')
    .split('')
    .map(v => v == v.toUpperCase() ?
      v.toLowerCase() :
      v.toUpperCase())
    .join('');
}