permissions-policy/resources/permissions-policy-private-state-token-issuance.html

<!DOCTYPE html>
<script>
'use strict';

window.onload = function() {
  // Check issuance operation availability for both Request and XMLHttpRequest.
  // They are tied to the same permission policy. They should be both enabled or disabled.
  let num_enabled = 2;
  try {
    const issue_request = new Request("https://issuer.example/", {
      privateToken: {
        version: 1,
        operation: "token-request"
      }
    });
  } catch (e) {
    num_enabled--;
  }

  try {
    const xhr = new XMLHttpRequest();
    xhr.open("GET", "https://issuer.example/");
    xhr.setPrivateToken({
      version: 1,
      operation: "token-request"
    });
  } catch (e) {
    num_enabled--;
  }
  parent.postMessage({
    type: 'availability-result',
    num_operations_enabled: num_enabled,
  }, '*');
}
</script>