codewars javascript exercises

Write a reverseWords function that accepts a string a parameter, and reverses each word in the string. Every space should stay, so you cannot usewords from Prelude.

Example:

reverseWords("This is an example!"); // returns  "sihT si na !elpmaxe"

function reverseWords(str) {
    return str.split(' ').map(x=>x.split('').reverse().join('')).join(' ');
}