Replace ouibounce by vanilla JS + Drupal dialog modal

Problem/Motivation

Ouibounce seems unmaintained and has several open issues.

Perhaps we should consider switching to a vanilla JS alternative (example code here: https://github.com/flowforfrank/exit-intent/blob/master/popup.js) and use the Drupal (native) dialog modal? (See https://www.drupal.org/project/dialog_native → )

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes