检索ajax函数内的每个Php循环变量

The images are stored inside separate folders.

Both the folders and the images are saved in the database. In my gallery page, they are shown from the database in two steps.

1. The folders are retrieved from the db and listed in the gallery page
2. while on-click of a folder, the images are to be listed. So far, I have passed the data from the database to the view and i have passed the foldernameto the ajax-call using onclick function

and my view code is as follows:

 <?php foreach($folder_info as $show){ ?>
<a class="glyphicon glyphicon-folder-close" style="font-size: 100px;" aria-hidden="true" onclick="imageslide('<?php echo $show['folder_id'] ?>');" ></a>
 <?php } ?>

Presently, I am not able to retrieve the passed $show['folder_id'] inside the <script> My ajax call is as follows:-

<script>

function imageslide(folderid){
alert(folderid);

$.ajax({
    url: "<?php echo site_url() ?>/welcome/getall_images",
    type: "GET",
    dataType: "json",
    data: {'id': folderid},
    success: function(data) {

        alert(data);
    }
}); </script>

Ajax Script

$.ajax({
    url: "<?php echo site_url() ?>/welcome/getall_images",
    type: "POST",
    dataType: "json",
    data: {id: folderid},
    success: function(data) {

        alert(data);
    }
}); </script>

Controller Code

function getall_images(){
   $folderId = $this->input->post('id');
}