Use ajax to filter mysql results with multiple checkbox option

JavaScript
,
1

Hi,
i am trying to build a search filter (like ebay site) using checkboxes. okay let me explain what i have done.
So, to get an idea of what type of thing i want please visite ebay site. i am also building ebay site as my project. visite this page please for better understanding https://www.ebay.com/sch/Other-Video-Games-Consoles/187/bn_1865232/i.html?_fsrp=1
i have build a web page completely look like this.
So, what i have done?
i have a search filter in which i have brand, plateform and model in which i get values from database.
Here is my code to get value from database same for plateform and model

<article class="search-item">
	<h6 id="show">Brand</h6>
	<ul>
	    <?php 
		if($cid)
                     {
                         $sql = "SELECT * FROM brands WHERE Cat_id = $cid";
                          $query = mysqli_query($connect,$sql);
                           $rs = mysqli_fetch_row($query);
                            if($rs == 0)
                                {
                                    echo "";
                                }
                                else 
                                {
                         while($brandrow = mysqli_fetch_array($query))
                            {
                              echo "<li><input type=\"checkbox\" name=\"brand\" value=\"".$brandrow['brand_id']."\" class=\"bcheckid check\" >".$brandrow['BrandName']."<li>";			
                          }
                        }
                    }
		?> 
	</ul>
</article>

i try using jquery ajax to search filter data on alerting a single value it works and show result but when i send this value using $.get method in jquery ajax i gives all html web page code, but i wants only the value. i am confused please help me. i only wants to value in $_GET method so please don’t use post method.
here is my jquery ajax code


        $(document).ready(function(){
            $(".check").click(function(){
            var cid = <?php echo $cid = $_GET['cid'] ?>;
            //alert(cid);
                //for brand 
                var brand = new Array();
                $("input[name=brand]:checked").each(function() {                   
                   brand.push($(this).val());
                   //alert(brand);  
                });
                //for plateform
                var plateform = new Array();
                 $("input[name=plateform]:checked").each(function() {                   
                    plateform.push($(this).val());
                    //alert(plateform);  
                 });

                 //for model 
                var model = new Array();
                $("input[name=model]:checked").each(function() {                   
                    model.push($(this).val());
                    //alert(model);  
                });
                 //$.get("item.php",{cid: cid,brand: brand,plateform: plateform,model: model
				var formdata = $("#checkform").serialize();
				$.ajax({
						type:"get",
						url:"result.php",
						data:formdata//only input						
				});
			});
        });

Here is my item.php code where i get search filter result.

$cid = $_GET['cid'];
	$plateform = $_GET['plateform'];
	$brandid = $_GET['brand'];
	$model_id  = $_GET['model'];
		if(!empty($cid))
		{
			$value = "Cat_id = $cid ";
		}
		else
		{
			$value = "";
		}
		
		$and = " AND ";
		if(!empty($brandid))
		{
			$brand = $and."brand_id = ".implode(",", $brandid); 
		}
		else 
		{
			$brand ="";
		}
		if(!empty($plateform))
		{
			$plateform_id = $and."plateform_id IN (".implode(",", $plateform)."$plateform)"; 
		}
		else 
		{
			$plateform_id ="";
		}
		if(!empty($model_id))
		{
			$model = $and."model_id = ".implode(",", $model_id); 
		}
		if($cid == 3)
		{
			$model ="";
		}

		
		
		
		
        echo $prodsql = "SELECT * FROM products
				INNER JOIN `condition` ON `products`.`condition_id` = `condition`.`condition_id`
				WHERE  $value $brand $plateform_id $model $pvalue  
				LIMIT $paginate->start, $paginate->limit;";

Again Please help me and thank you soooo much in advance. and sorry for my bad english.