I use silviomoreto / bootstrap-select for select. Here is silviomoreto / bootstrap-select documentation: silviomoreto.github.io/bootstrap-select/
So I have a select and collaplsing block.
That block have to collapse by selecting any options in select. For example : I choose any option then hidden block must appears.
<select class="selectpicker" multiple title="Choose category">
<option>House help</option>
<option>Buy</option>
<option>Drivers</option>
<option>Holidays</option>
<option>Animals</option>
</select>
<!-- HIDDEN BLOCK -->
<div class="hidden-input" id="hidden-input" style="display:none;">
<div class="panel panel-default" >
<div id="collapseThree" class="panel-collapse collapse">
<div class="panel-body">
<select class="selectpicker" multiple title="Choose subcategory">
<option>1</option>
</select>
</div>
</div>
</div>
</div>