使用對象relatedTarget的屬性event來訪問觸發模態打開的元素
$('#exampleModal').on('shown.bs.modal', function(e){
const buttonId = e.relatedTarget.id;
$(this).find('.modal-body').text(`Button id = ${buttonId}`);
});
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" ></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" ></script>
<!-- Button trigger modal -->
<button id="btn_1" type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
Modal Button 1
</button>
<button id="btn_2" type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
Modal Button 2
</button>
<!-- Modal -->
<div class="modal fade" id="exampleModal" aria-hidden="true">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="exampleModalLabel">Modal title</h5>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<div class="modal-body"></div>
</div>
</div>
</div>
