We are absolutely delighted to unveil the newly added Custom JS option to our Back to Top 
The Custom JS option empowers you to enhance the widget with your own script, giving you the freedom to add extra features without relying on our developers.
Important: Custom JS operates only upon widget installation, but not in preview mode.
You can find this option at the bottom of the Settings tab:
Custom JS Editor has a Validate button, which allows you to check the code validity.
Reminder: the code entered is the body of the function that will be executed when the widget loads on the page. Do not include any <script> tags.
Feel free to ask any questions in this thread 