async function postData(url = "", data = {}) {
  // Default options are marked with *
  const response = await fetch(url, {
    method: "POST", // *GET, POST, PUT, DELETE, etc.
    mode: "cors", // no-cors, *cors, same-origin
    cache: "no-cache", // *default, no-cache, reload, force-cache, only-if-cached
    credentials: "same-origin", // include, *same-origin, omit
    headers: {
      "Content-Type": "application/json",
      // 'Content-Type': 'application/x-www-form-urlencoded',
    },
    redirect: "follow", // manual, *follow, error
    referrerPolicy: "no-referrer", // no-referrer, *no-referrer-when-downgrade, origin, origin-when-cross-origin, same-origin, strict-origin, strict-origin-when-cross-origin, unsafe-url
    body: JSON.stringify(data), // body data type must match "Content-Type" header
  });
  return response.json(); // parses JSON response into native JavaScript objects
}

postData("https://example.com/answer", { answer: 42 }).then((data) => {
  console.log(data); // JSON data parsed by `data.json()` call
});

pipeline {
    stages { ... }
    post {
       // only triggered when blue or green sign
       success {
           slackSend(channel: 'alerts-testing', color: 'good', message: ":party_parrot: NOTIFICATION: NEW RELEASE ${newRelease} WILL BE CREATED AUTOMATICALLY :party_parrot:")
       }
       // triggered when red sign
       failure {
           slackSend(channel: 'alerts-testing', color: 'RED', message: ":alarm_clock: NOTIFICATION: NEW RELEASE ${newRelease} WITH SOME FAILURE :alarm_clock:")
       }
       // trigger every-works
       always {
           slackSend ...
       }
    }
}