message: Change Javascript -> JavaScript
diff: @@ -250,7 +250,7 @@ jest.mock('./sound-player', () => {
  **_Note: Arrow functions won't work_**
  Note that the mock can't be an arrow function because calling `new` on an arrow
  -function is not allowed in Javascript. So this won't work:
  +function is not allowed in JavaScript. So this won't work:
  ```javascript
  jest.mock('./sound-player', () => {
  