document.addEventListener('DOMContentLoaded', async () => {
  const signupForm = document.querySelector('#signup-form');
  if (signupForm) {
    signupForm.addEventListener('submit', async (e) => {
      e.preventDefault();

      // Grab reference to the emailInput. The email address
      // entered will be passed to the server and used to create
      // a customer. Email addresses do NOT uniquely identify
      // customers in Stripe.
      const emailInput = document.querySelector('#email');

      // Create a customer. This will also set a cookie on the server
      // to simulate having a logged in user.
      const {customer} = await fetch('/create-customer', {
        method: 'post',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify({
          email: emailInput.value,
        }),
      }).then(r => r.json()); 

      // Redirect to the pricing page.
      window.location.href = '/prices.html';
    });
  } else {
    alert("No sign up form with ID `signup-form` found on the page.");
  }
});