How to create gallery using custom field in Wordpress?

//js script needs to be queued in functions php for admin pages only

 jQuery(document).ready(function($){

    // Instantiates the variable that holds the media library frame.
    var meta_image_frame;

    // Runs when the image button is clicked. You need to insert ID of your button
    $('#button-id').click(function(e){

        // Prevents the default action from occuring.
        e.preventDefault();

        // If the frame already exists, re-open it.
        if ( meta_image_frame ) {
            meta_image_frame.open();
            return;
        }

        // Sets up the media library frame
        meta_image_frame = wp.media.frames.meta_image_frame = wp.media({
            title: 'Choose image(s)',
            multiple: 'add',
            button: { text:  'Choose image(s)' },
            library: { type: 'image' }
        });

        // Runs when an image is selected. You need to insert ID of input field
        meta_image_frame.on('select', function(){
            var selection = meta_image_frame.state().get('selection');
            var size = 'thumbnail'
            selection.map(function(attachment) {
                attachment = attachment.toJSON();
                $("#input-field-ID").val($("#input-field-ID").val() +"<li><a href=" +attachment.url+ " target=_blank><img src=" +attachment.sizes[size].url+ " /></a></li>");
            });

        });

        // Opens the media library frame.
        meta_image_frame.open();
    });
});