JS for touch subnav. Requires: Modernizr (expects the touch class) and hover classes in CSS.

subnav.js

$(function() {
  if ($('html').hasClass('touch'))
	{
		$('html').click(function(e) {
			$('nav > ul > li').removeClass('hover');
		});
		
	    $('nav > ul > li').click(function(e) {
	    	    
	    	if (!$(this).hasClass('hover') && $(this).has('ul.subnav').length > 0)
	    	{
		        e.preventDefault();
		        e.stopPropagation();
	        }
	        
			$('nav > ul > li').removeClass('hover');
	        $(this).toggleClass('hover');
	    });
	}
});

Alternatively, using Bootstrap's dropdown menus, you may want to disable to the forced click on Desktops when using data-toggle="dropdown".

Still using Modernizr:

// Disable data-toggle on dropdown
if (!$('html').hasClass('touch'))
{
    $('.nav a').click( function(e) {
        $(this).removeAttr('data-toggle');
    });
}

For Bootstrap:

if ($('html').hasClass('touch'))
{
    $('html').click(function(e) {
        $('.navbar-nav > li').removeClass('hover');
    });

    $('.navbar-nav > li').click(function(e) {

        if (!$(this).hasClass('hover') && $(this).has('ul.dropdown-menu').length > 0)
        {
            e.preventDefault();
            e.stopPropagation();
        }

        $('.navbar-nav > li').removeClass('hover');
        $(this).toggleClass('hover');
    });
}

Load Fastclick (https://github.com/ftlabs/fastclick) for this script to work in iOS8.