Select all / Unselect all in Bootstrap Select plugin

Answer 1

You can use my functions :

first change your code

<option value="All" selected="selected">All Ratings</option>

to

<option value="All" id="target" selected="selected">All Ratings</option>

and second add between your <script> tags

$( "#target" ).toggle(function() {
  selectAll($( "#divRatings" ))
}, function() {
  selectClear($( "#divRatings" ))
});

function selectAll(element){//Select All Function
    element.prop('selected', true);
    element.selectpicker('refresh');
}
function selectClear(element){//Clear All Function
    element.prop('selected', false);
    element.selectpicker('refresh');
}