Script to add blank pages before last to increase pages to multiples of 4 for booklet printing

[Nicky5E9E]

I need an automate for a large numbers of pdfs,  I need to print booklets so the final pdfs must always be in page multiples of 4 but I need the last page of the original pdf to stay as the last page with blank pages inserted before the last page. (first page of pdf is front cover. last page of pdf is back cover)

EG:  3page pdf  becomes a 4 page   a 5 page pdf becomes an 8 page or a 31 page pdf  becomes a 32 page

[try67]

Does the size of the pages to insert matter? Which version of Acrobat do you have?

Edit: fixed a typo

[Nicky5E9E]

I have the latest version of Acrobat Pro DC installed on our Design Mac in necessary but I would prefer to be running this in the background automated on a PC running Acrobat 8.

The documents are A4 portrait, however the pdfs would then be dropped into a hot folder on a RIP which would impose the pages for output.

[try67 · Accepted solution]

You can't use Acrobat as a background process, and Acrobat 8 is very old and not supported by Adobe.

However, you can achieve it by running this code from an Action (or Batch Process, as it was formerly called):

while (this.numPages%4!=0) this.newPage(this.numPages-1, 595, 842);

[Nicky5E9E]

Fantastic, this works perfectly. 

Can you recommend any resources where I can learn more about this scripting/code  starting from being  a complete beginner?