Spinners
Para crear un spinner / cargador, use la clase .spinner-border.
Ejm
<div class="spinner-border"></div>
Spinners coloreados
Use cualquier utilidad de color de texto para agregar un color a la ruleta.
Ejm
<div class="spinner-border text-muted"></div>
<div class="spinner-border text-primary"></div>
<div class="spinner-border text-success"></div>
<div class="spinner-border text-info"></div>
<div class="spinner-border text-warning"></div>
<div class="spinner-border text-danger"></div>
<div class="spinner-border text-secondary"></div>
<div class="spinner-border text-dark"></div>
<div class="spinner-border text-light"></div>
Spinners crecientes
Use la clase .spinner-grow si deseas que el spinner / cargador crezca en lugar de "spin":
Ejm
<div class="spinner-grow text-muted"></div>
<div class="spinner-grow text-primary"></div>
<div class="spinner-grow text-success"></div>
<div class="spinner-grow text-info"></div>
<div class="spinner-grow text-warning"></div>
<div class="spinner-grow text-danger"></div>
<div class="spinner-grow text-secondary"></div>
<div class="spinner-grow text-dark"></div>
<div class="spinner-grow text-light"></div>
Tamaño del Spinner
Use .spinner-border-sm o .spinner-grow-sm para crear una ruleta más pequeña:
Ejm
<div class="spinner-border spinner-border-sm"></div>
<div class="spinner-grow spinner-grow-sm"></div>
Botones Spinner
También puede agregar Spinners a un botón, con o sin texto:
Ejm
<button class="btn btn-primary">
<span class="spinner-border spinner-border-sm"></span>
</button>
<button class="btn btn-primary">
<span class="spinner-border spinner-border-sm"></span>
Loading..
</button>
<button class="btn btn-primary" disabled>
<span class="spinner-border spinner-border-sm"></span>
Loading..
</button>
<button class="btn btn-primary" disabled>
<span class="spinner-grow spinner-grow-sm"></span>
Loading..
</button>