Removes the need for username input upon signup for 3scale-based developer portals

3scale-username.js

// Tactic: highjack form submission, then make value of username field the same as email field, then submit the form

document.addEventListener('DOMContentLoaded', function() {
  
  // First, hide the whole username form row
  var style = document.createElement('style'),
      css = '#signup_form fieldset:nth-of-type(2) .form-group:nth-child(2) { display: none; }';

  style.type = 'text/css';
  if (style.styleSheet){
    style.styleSheet.cssText = css;
  } else {
    style.appendChild(document.createTextNode(css));
  }
  document.head.appendChild(style);
  
  // Then, move on to input value cloning
  var form = document.getElementById('signup_form'),
      email = document.getElementById('account_user_email'),
      username = document.getElementById('account_user_username'),
      button = document.getElementById('signup_button');

  function submitForm() {
    // Make username same as email, but strip the @ part
    username.value = email.value.match(/^([^@]*)@/)[1];
    form.submit();
  }

  // highjack button click
  button.addEventListener('click', function(event) {
    event.preventDefault();
    submitForm();
  });
});