Create New Presentation using PowerPoint Web Add-ins

Hi,

I am developing a web add-ins for PowerPoint to apply custom template in a new presentation. I have created task pane and displaying the custom templates but when i go to create a new presentation using PowerPoint.createPresentation() method using JavaScript (Office.JS) then it gives me error as 'PowerPoint' is undefined.

I explored mostly Microsoft articles regarding this but didn't find how to use PowerPointApi 1.1 for this. Can you help me to resolve this issue?

I am following this article:

https://docs.microsoft.com/en-us/office/dev/add-ins/powerpoint/powerpoint-add-ins#create-a-presentation

Thanks in advance