How to add pull-right to a Button in React Bootstrap?

If you take a look at React-Bootstrap Components, you'll see that prop bsStyle of component Button only accepts the following values:

"success", "warning", "danger", "info", "default", "primary", "link"

based on its visual appearance as mentioned in the warning message. If you intend to use Bootstrap's pull-right class, just use the className attribute which will set the class of that component:

<Button className="pull-right" bsStyle="danger" bsSize="small" onClick={() => {alert('do stuff')}}>
    <Glyphicon glyph="trash" />
</Button>

Bootstrap 4 Update

Now that React Bootstrap uses Bootstrap 4, use float-right, float-sm-right, etc.:

<Button className="float-right" bsStyle="danger" bsSize="small" onClick={() => {alert('do stuff')}}>
    <Glyphicon glyph="trash" />
</Button>