Refactor code.

Author: russom-g

practice-tdd/count.js

@@ -1,7 +1,7 @@
 export function countChar(stringOfCharacters, findCharacter) {
   let count = 0;
-  for (let i = 0; i < stringOfCharacters.length; i++) {
-    if (stringOfCharacters[i] === findCharacter) {
+  for (const char of stringOfCharacters) {
+    if (char === findCharacter) {
       count++;
     }
   }