Accordion "Left Navigation" (Quick Launch) for SharePoint 2013

For Expand/collapse "Left Navigation (Quick Launch) for sharepoint 2013
Copy the below code and paste in Master page


jQuery(document).ready(function () {

 /*set dynamic css logic*/

 if($('#sideNavBox .menu-item.selected').length){

  //propagates the selected class, up the three.

  $('li.static').removeClass('selected');

  $('#sideNavBox .menu-item.selected').parents('li.static').addClass('selected');

  //collapses top siblings of selected branch

  $('#sideNavBox .menu-item.selected').parents('li.static').last().siblings()

   .find('> ul').hide();

 }

 else $('#sideNavBox .root.static > li.static > ul').hide();

 /*set accordion effect*/

 $('#sideNavBox .root.static > li.static').each(function(){

  if($(this).find('ul').length){

   $(this).addClass('father').click(function(){

    if($(this).children('ul').css('display') != 'none'){

     $(this).removeClass('selected').children('ul').slideUp();

    }

    else {

     /*collapse-siblings*/

     $(this).siblings().removeClass('selected').children('ul').slideUp();

     /*expand*/

     $(this).addClass('selected').children('ul').slideDown();

    }

    /*added: stop event propagation to link nodes*/

    $('a.static').click(function(event) {

        event.stopPropagation();

    });

    /*added*/

   });

  }

 });

});