Beliyadm

$('select').on('change', function() {
	var thisform = $(this);
	var form_data = thisform.serialize();
	$.ajax({
		type: 'POST',
		url: 'ajax.php',
		data: form_data,
		target:	'',
		success: function(response){
		}
	});
});

$('.slider_blocks').on('click', 'li', function(){
		var lindex = $(this).index();
		$( ".slider" ).slick('slickGoTo', parseInt(lindex)); // меняем слад на нужный индекс
		$('.slider_blocks li').removeClass('active'); // change class
		$(this).addClass('active');
});

$('.slider').on('afterChange', function(event, slick, currentSlide, nextSlide){
		var slideIndex = $(this).index();
		$('.slider_blocks li').removeClass('active');
		$('.slider_blocks li').eq(currentSlide).addClass('active')
	});