Bootstrap 4 Spinner Buttons

Example

<button class="btn btn-warning">
  <span class="spinner-border spinner-border-sm"></span>
</button>

<button class="btn btn-warning">
  <span class="spinner-border spinner-border-sm"></span>
  Loading..
</button>

<button class="btn btn-warning" disabled>
  <span class="spinner-border spinner-border-sm"></span>
  Loading..
</button>

<button class="btn btn-warning" disabled>
  <span class="spinner-grow spinner-grow-sm"></span>
  Loading..
</button>

Result: