这是一项功能，当您显示模式，并在您隐藏它时删除.

This is a feature, class modal-open gets added to the HTML body when you show the modal, and removed when you hide it.

这使得滚动条消失，因为引导 css 说

This makes the scrollbar disappear since the bootstrap css says

.modal-open {
    overflow: hidden;
}

您可以通过指定来覆盖它

You can override this by specifying

.modal-open {
    overflow: scroll;
}

在你自己的 css中.