It will be better to make your file structure like this:
|__ src
| |
| |__ server
| | |___ handlers.js
| | |___ router.js
| | |___ server.js
| |
| |__ test
| | |___ tests.js
| |__ apis
| |___ apiRequests.js
|
|__ public
|__ css
| |___ resets.css
| |___ main.css
|
|__ js
| |___ dom.js
| |___ requests.js
|
|__ index.html
It will be better to make your file structure like this: