Is possible in Google Gantt chart plug-in the date to day conversion?

Hello,

I am using Google Gantt chart for my current project for display dependency task data like Task Name, Start Date & Time, Due Date & Time and Duration.

Here I want to display Day (Sunday, Monday, Tuesday .....Saturday) instead of date can any one help me to how to we achieve this for this Plug-in.

I have tried these Appian Date to Day Convert Functions (text and weekday) but when write the format like "dddd". the plug-in throughs an error as below.

Thanks in Advance,

Mahesh