website/register/register.js

const url = 'https://exozy.me/new/'
const form = document.querySelector('form')

form.addEventListener('submit', (e) => {
  e.preventDefault()
  
  const data = new Object()
  
  for (const s of ['code', 'firstname', 'lastname', 'email', 'username', 'password']) {
    data[s] = document.getElementsByName(s)[0].value
    if (data[s] == '') {
      alert('Please fill out the form completely')
      return
    }
  }

  if (/^[a-z0-9]+$/.test(data['username']) === false || (data['username'][0] >= '0' && data['username'][0] <= '9')) {
    alert('Username can only contain lowercase letters and numbers and can\'t start with a number')
    return
  }

  if (data['password'] != document.getElementsByName('confirmpassword')[0].value) {
    alert('Passwords don\'t match')
    return
  }

  console.log(data)
  
  fetch(url, {
    method: 'POST',
    body: JSON.stringify(data),
  }).then((response) => {
    alert(response.statusText)
  })
})