Get iframe by message event

Question

I have several iframes with same origin (but different pathnames) on the page.
Every iframe emits message event through postMessage.
Parent window listens these events:

window.addEventListener('message', function(event) {
  /* Get iframe element by event */
});

I want to get source iframe element for every event.

The important limitation is that I have no access to event.source.contentWindow because of cross-origin.

UPD: answer below

Answer 1

The solution is to compare event.source and iframe.contentWindow:

function getFrameByEvent(event) {
  return [].slice.call(document.getElementsByTagName('iframe')).filter(function(iframe) {
    return iframe.contentWindow === event.source;
  })[0];
}

Here's more modern version:

function getFrameByEvent(event) {
  return Array.from(document.getElementsByTagName('iframe')).filter(iframe => {
    return iframe.contentWindow === event.source;
  })[0];
}