bootstrap 4 loading spinner on button click code example
Example 1: font awesome 4 animated loading spinner
<i class="fa fa-spinner fa-spin fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
<i class="fa fa-circle-o-notch fa-spin fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
<i class="fa fa-refresh fa-spin fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
<i class="fa fa-cog fa-spin fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
<i class="fa fa-spinner fa-pulse fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
Example 2: 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>