I have to write a PDF plugin that can upload the currently opened document to a remote server upon clicking a button.

I found "Acrobat DC SDK" which describe there are three development paths:

• JavaScript API
• Plugins
• Interapplication Communication

Above mentioned approaches are explained here: https://opensource.adobe.com/dc-acrobat-sdk-docs/acrobatsdk/choose.html

I have skimmed through "Acrobat JavaScript Guide", but I am unable to conclude can I create a standalone script using Only JavaScript API? or are they designed to be called from Adobe Plugins?

Here is the link to the Acrobat JavaScript guide: https://www.adobe.com/go/acrobatsdk_jsdevguide

Also please refer me to the "Acrobat DC SDK" samples or tutorials which can help me to achieve this task.