How to autochage the dropdown option for every 30 sec
<p>I have done the dropdown with the previous and next.
I want to know how can I change the dropdown option value automatically for every n seconds.
<a href="https://jsfiddle.net/wmwayysz/" rel="nofollow noreferrer">https://jsfiddle.net/wmwayysz/</a></p>

<pre><code> &lt;script  
 src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"&gt;    
 &lt;/script&gt;
 &lt;button type="button" id="prev"&gt;Previous&lt;/button&gt;
&lt;select id="selectBox" onchange="currentSlide(value);" class="selectpicker"&gt;
 &lt;option value="1" class="options"&gt;Electronics&lt;/option&gt;
 &lt;option value="2" class="options"&gt;Clothing&lt;/option&gt;
 &lt;option value="3" class="options"&gt;Health&lt;/option&gt;
  &lt;option value="4" class="options"&gt;Food&lt;/option&gt;
 &lt;option value="5" class="options"&gt;Travel&lt;/option&gt;
 &lt;option value="6" class="options"&gt;Mobiles&lt;/option&gt;
 &lt;option value="7" class="options"&gt;Grocery&lt;/option&gt;
 &lt;option value="8" class="options"&gt;Recharge&lt;/option&gt;
 &lt;option value="9" class="options"&gt;Furniture&lt;/option&gt;
</code></pre>

<p><br>
       Next</p>

<pre><code> $.fn.loopNext = function(selector) {
   var selector = selector || '';
     return this.next(selector).length ? this.next(selector) :       
    this.siblings(selector).addBack(selector).first();
   }
  $.fn.loopPrev = function(selector) {
    var selector = selector || '';
    return this.prev(selector).length ? this.prev(selector) :    
      this.siblings(selector).addBack(selector).last();
   }
    $("#next").click(function() {
    $('#selectBox &gt; option:selected')
        .removeAttr('selected')
       .loopNext('option')
          .prop('selected', 'selected');
    });

  $("#prev").click(function() {
     $('#selectBox &gt; option:selected')
     .removeAttr('selected')
       .loopPrev('option')
         .prop('selected', 'selected');
   });

  function currentSlide(selectionValue) {
      console.log(selectionValue);
    }
</code></pre>