HTML

bootstrap loader

<div class="spinner-grow text-primary" role="status">
  <span class="sr-only">Loading...</span>
</div>
<div class="spinner-grow text-secondary" role="status">
  <span class="sr-only">Loading...</span>
</div>
<div class="spinner-grow text-success" role="status">
  <span class="sr-only">Loading...</span>
</div>
<div class="spinner-grow text-danger" role="status">
  <span class="sr-only">Loading...</span>
</div>
<div class="spinner-grow text-warning" role="status">
  <span class="sr-only">Loading...</span>
</div>
<div class="spinner-grow text-info" role="status">
  <span class="sr-only">Loading...</span>
</div>
<div class="spinner-grow text-light" role="status">
  <span class="sr-only">Loading...</span>
</div>
<div class="spinner-grow text-dark" role="status">
  <span class="sr-only">Loading...</span>
</div>

bootstrap loader

<div class="text-center">
  <div class="spinner-border" role="status">
    <span class="sr-only">Loading...</span>
  </div>
</div>

bootstrap loader

<button class="btn btn-primary" type="button" disabled>
  <span class="spinner-border spinner-border-sm" role="status" aria-hidden="true"></span>
  <span class="sr-only">Loading...</span>
</button>
<button class="btn btn-primary" type="button" disabled>
  <span class="spinner-border spinner-border-sm" role="status" aria-hidden="true"></span>
  Loading...
</button>

bootstrap loader

<div class="d-flex align-items-center">
  <strong>Loading...</strong>
  <div class="spinner-border ml-auto" role="status" aria-hidden="true"></div>
</div>

bootstrap loader

<div class="spinner-grow" role="status">
  <span class="sr-only">Loading...</span>
</div>

bootstrap loader

<div class="spinner-border spinner-border-sm" role="status">
  <span class="sr-only">Loading...</span>
</div>
<div class="spinner-grow spinner-grow-sm" role="status">
  <span class="sr-only">Loading...</span>
</div>

bootstrap loader

<div class="clearfix">
  <div class="spinner-border float-right" role="status">
    <span class="sr-only">Loading...</span>
  </div>
</div>

bootstrap loader

<button class="btn btn-primary" type="button" disabled>
  <span class="spinner-grow spinner-grow-sm" role="status" aria-hidden="true"></span>
  <span class="sr-only">Loading...</span>
</button>
<button class="btn btn-primary" type="button" disabled>
  <span class="spinner-grow spinner-grow-sm" role="status" aria-hidden="true"></span>
  Loading...
</button>

bootstrap loader

σsubject = "database" and price = "450" or year > "2010"(Books)

bootstrap loader

σsubject = "database"(Books)