JavaScript to store the file open count in a text file

Question

Hi,
Can we write a javascript in pdf such that when the pdf file is opened, the file open count is stored in a text file locally. Every time, the pdf file is opened, the count should be incremented in the text file. This is basically to check how many time a particular pdf file is opened by an user.
The text file path should be defined in the javascript.

Answer 1

Reader is not able to write to a text file, so you will have to use a global persistent variable.
The script you would use is very simple, and should be set up to run when the document is opened. You can do this by creating a document-level script. The code can look something like:
// Set up a routine that creates
// and/or increments a global count
// variable that keeps track of how
// many times the document has been
// opened on this machine
(function () {
    // Set up the variable name
    // This needs to be unique for each document
    var count_var = "my_doc_open_count";
    // Create global variable if it doesn't already exist
    // and make it persistent
    if (typeof global[count_var] === "undefined") {
        global[count_var] = 0;
        global.setPersistent(count_var, true);
    // Increment the counter
    global[count_var] += 1;
    // Notify user how many times the document has been opened
    // This is mostly for testing, so comment it out if not needed
    app.alert("This document has been opened " + global[count_var] + " times.", 3);
Read the Acrobat JavaScript reference and the accompanying scripting guide for more information. Note that Reader users may have to enable the use of globally persistent variables for this to work.
George