What an awesome update, guys!
The Custom JS feature is now available in our Chats 
With the Custom JS option, you can add extra features to the widget by writing your own script. You don’t need to reach out to our devs, as you have the freedom to customize it yourself.
Important: Custom JS operates only upon widget installation, but not in preview mode.
You can find this option on the Appearance 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.