The jQuery plugin appear select elements with intuitive multiselection, searching, and much more. Bootstrap-select requires jQuery, Bootstrap’s dropdown component, and Bootstrap's CSS. Check more info on the page.
Use <optgroup> to group select options
Add .show-tick class to show checkmark on selected options
This library will read title attribute for placeholder
You can use button color modifier classes
Set data-width to set select element width
Enable select all and deselect all helper buttons
Use is-{valid|invalid} classes for validation states
Resize select elements by adding .form-control-{lg|sm} classes