How do I pass a value out of a Wordpress Thickbox?

I am currently working on a custom Wordpress plugin which requires the user to create a list in a form, and so to help them populate their list, I have implemented the Wordpress Thickbox. I have made the Thickbox display, with the content I would like, however what I am struggling to do is pass the data back to the original form.

The Original Form is like this:

<input name="input_that_wants_data" id="input_for_data" type="text" />
<a href="#TB_inline?width=600&height=550&inlineId=my-content-id" class="thickbox">Click Here for Modal</a>

Just like you would expect any form to be. Basically I want the information from the modal to pass my string back to the input_for_data

The code inside the modal has multiple table rows like this:

<td><input type="checkbox" class="modal_checkbox_class" value="'.$data->value.'"></td>

Basically what I would like to do is build an array of the values of each clicked checkbox, and then use the split function of Javascript to turn it into a string which I would return to the input field outside of the modal.

Any and all help is greatly appreciated. I would prefer a Javascript/JQuery solution to this

I used this tutorial to do something that you want: https://code.tutsplus.com/tutorials/getting-started-with-the-wordpress-media-uploader--cms-22011

My code looks like this:

    function renderMediaUploader() {
    'use strict';

    var file_frame, image_data;

    /**
     * If an instance of file_frame already exists, then we can open it
     * rather than creating a new instance.
     */
    if ( undefined !== file_frame ) {

        file_frame.open();
        return;

    }

    /**
     * If we're this far, then an instance does not exist, so we need to
     * create our own.
     *
     * Here, use the wp.media library to define the settings of the Media
     * Uploader. We're opting to use the 'post' frame which is a template
     * defined in WordPress core and are initializing the file frame
     * with the 'insert' state.
     *
     * We're also not allowing the user to select more than one image.
     */
    file_frame = wp.media.frames.file_frame = wp.media({
         title: 'Select or Upload Media Of Your Chosen Persuasion',
          button: {
            text: 'Use this media'
          },
        multiple: true
    });

    //add items from thickbox to table
    file_frame.on( 'select', function() {

        var attachment = file_frame.state().get('selection').toJSON();

        jQuery.each(attachment, function(i, val){
            jQuery('table').show();
            jQuery('table tbody').append('<tr class="table_row"><td class="col-sm-2"><img class="img-responsive" src="'+val.url+'"></td><td class="col-sm-8"><input style=" display: block;" type="text" name="entry[url][]" value="'+ val.url +'"></td></tr>');
        });


    });

    // Now display the actual file_frame
    file_frame.open();

}

(function( $ ) {
    'use strict';

    $(function() {
        $( '#set-footer-thumbnail' ).on( 'click', function( evt ) {

            // Stop the anchor's default behavior
            evt.preventDefault();

            // Display the media uploader
            renderMediaUploader();

        });

    });

})( jQuery );