Usage

var receiveMessage = function (evt) {
  if (evt.data === 'MM:3PCunsupported') {
    document.getElementById('result').innerHTML = 'not supported';
  } else if (evt.data === 'MM:3PCsupported') {
    document.getElementById('result').innerHTML = 'supported';
  }
};

window.addEventListener("message", receiveMessage, false)
@github

Result

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