data-bs-backdrop
html bootstrap5 Sample
js アラートを閉じるボタンでしか消えないモーダル:data-bs-backdrop
<button type="button" class="btn btn-primary" data-bs-toggle="modal"
data-bs-target="#staticBackdropLive">×でしか閉じないモーダル</button>
<div class="modal fade" id="staticBackdropLive" data-bs-backdrop="static" data-bs-keyboard="false" tabindex="-1"
aria-labelledby="staticBackdropLiveLabel" aria-hidden="true">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="staticBackdropLiveLabel">Modal title</h5>
<button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
</div>
<div class="modal-body">
<p>I will not close if you click outside me. Don't even try to press escape key.</p>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Understood</button>
</div>
</div>
</div>
</div>