Module development and code questions

Hoping someone might be able to help me out. I have a custom Drupal 8 module which has a webform composite element with some settings/properties that are fields where I can either enter a webtoken to capture some data from the form or simply enter some data for later retrieving on the webform handler side. The issue is that I thought this data would be included in $_POST but it's not so I'm trying figure out how I can retrieve the data after the form is submitted. FYI, I don't even see this data being stored in the "webform_submission_data" table so not sure where it's being saved.

Hi All,
I'm wondering if there's any sort of JavaScript API for the Media/Media Library modules. I'm writing a custom module that has some front end code that needs to detect when a media item is selected (or removed) from a Media field. I also need to be able to grab the src URL of the thumbnail, so I need to wait for the AJAX call to finish before the event triggers. Is there a way for me to do this? Similar to how for CKEditor there's CKEDITOR.instances[id].on('change', function(){}) I'm hoping for an event to hook into.

I'm using hook_form_alter on a node (content type):

Hi,

I try to evaluate if we can migrate our website "FloraWeb" to Drupal.

The main content on FloraWeb is scientific data about plants fetched from our Oracle database, here an example:
https://www.floraweb.de/xsql/artenhome.xsql?suchnr=20421&

I am attempting to add, to a webform, a custom setting within in the settings tab (either a third party setting or one in a custom block) that will be a drop down list of all the elements listed in the build tab. The intent is, based on the author's selection, that the selected element will be the one whose information is labeled as the main piece of information for our API.

(I had images of the "Settigns" page and the "Build" page but can't figure out how to add them)

The problem I'm having is three-fold:

Hi, I have received a lot of help on custom forms but I am still missing something and I need an explanation
In the buildForm function I insert the fields I need, in this case a button called crea and a table field called table_dispo
The table_dispofield I fill it with the result of a select
Pressing the button crea launch a new query and the table_dispo field should be updated with the new results.
I inserted a wrapper inside the button and inserted the iD inside the table field and it should update the table field but it doesn't.