1.html

2
<script src="bm.js"></script>
<script>
  var mb = messageBroadcaster;

  mb.on('elo', function(data){
    document.body.innerHTML += data;
  });

</script>

<button onclick="mb.fire('elo', 'yo2');">EMIT EVENT</button>

2.html

2
<script src="bm.js"></script>
<script>
  var mb = messageBroadcaster;

  mb.on('elo', function(data){
    document.body.innerHTML += data;
  });

</script>

<button onclick="mb.fire('elo', 'yo2');">EMIT EVENT</button>

index.html

<style>
  iframe {
    width: 300px;
    height: 300px;
    border: 3px solid #f0f;
  }
</style>
<script src="bm.js"></script>

<script>
  var mb = messageBroadcaster;

  mb.on('elo', function(data){
    document.body.innerHTML += data;
  });

</script>

<iframe src="1.html"></iframe>
<iframe src="2.html"></iframe>

<button onclick="mb.fire('elo', 'yo');">EMIT EVENT</button>
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