<script>
  var paragraph = document.getElementById('paragraph');

  var cabins = [1,2,3];

  for (var i = 0; i < cabins.length; i++) {
    paragraph.innerHTML += "Cabin " + cabins[i] + "<br><br><button id='cabin" + cabins[i] +"' onclick='purchaseCabin()'>Purchase</button><br><br>"
  }

  function purchaseCabin() {
    var cabinId = this.id;
    console.log(cabinId);
  }
</script>