In the back-office, when we create a page, we can add sections and rows in which we can create elements. These elements are for example text boxes, images, buttons, and other Visual Composer mappings manually declared in
functions.php for example, using the function
When we want to add one of these elements to a section/row, we click on its icon and another pop-in is shown. The latter contains fields required by the element (the text and the image for a button, etc.).
I saw that an AJAX query is sent asking for
admin-ajax.php and then
I can look for PHP hooks and filters too, you know.