How can I put JavaScript code into a PDF document?

JavaScript is typically tied to objects in a PDF document. For example, if you want the user to be able to print the PDF by clicking a Print button, follow the steps below:

• Add a button to the form (done under advanced editing)
• Right click on the button and go to properties
• Click the actions tab
• Under Select Action: choose Run a JavaScript
• put print(); in the code window

Here's a link to an old (Acrobat 7.0.5) Acrobat JavaScript Scripting Reference to get you started.

Fresh Links 22/06/2020

• Adobe Acrobat 7.0 JavaScript Scripting Reference
• JavaScript for Acrobat API Reference

You didn't stipulate a constraint for language, so you can use Python to achieve this. The library PyPDF2 has a class called addJS that works. Here is an example from the REPL:

mypdf.addJS("this.print({bUI:true,bSilent:false,bShrinkToFit:true});")

and here is a link to the documentation. Note, that you need to have python3 installed (2.7 is going away at the end of 2019) and then run pip3 install PyPDF2 or similar to install the library and then load it via import PyPDF2. Hopefully that helps.