Indeed GREP is thinking in the wrong direction. GREP is nothing more than a (very) fancy search-and-replace function.

That said: the functionality you are looking for – math calculations – can be done inside InDesign through a script! A script has access to the Text Variables in your current document (https://helpx.adobe.com/indesign/using/text-variables.html) and so it can change their contents. And JavaScript (my preferred InDesign scripting language) has built-in operators to retrieve the current date.

If you write the above down in a basic script, you’ll practically have what you ask for; but then the problem is when to run this script. After all, if you cannot remember to change a year value once a year, you’d also be prone to forgetting to run the script at least once a year (“at least once”, because once run, it’d set the variable to the correct value for the entire year to come).

It’s far easier if your friendly InDesign kept the variable up-to-date. And it can! Here, copy this rather short-but-sweet script into the Extendscript Toolkit Editor and save it as a new file “set_experience_variable.jsx” in a folder called “Startup Scripts” – not your regular “Scripts Panel” folder. In case this is new for you, see “Download the script” in https://creativepro.com/add-missing-options-to-the-book-menu.php for a practical step-by-step instruction. (But no need to download that script.)

//DESCRIPTION:Write date difference in variable
// A Jongware Script 12-Jul-2019
#targetengine "set_experience_variable"

function check_and_set_variable (event)
{
var theDoc = event.parent;
if (theDoc instanceof Document)
{
var tvar = theDoc.textVariables.item('experience');
if (tvar.isValid && tvar.variableType == VariableTypes.CUSTOM_TEXT_TYPE)
{
tvar.variableOptions.contents = String(new Date().getFullYear() - 1976)
}
}
}

For the script to work at start-up, you must quit and restart InDesign once you copied this into the Startup Scripts folder, but afterwards it should fire automatically. What it does is, every time you OPEN an existing document, it checks if there is a Text Variable called “experience” in that document. If it is, it double-checks if its type is “Custom Text” (so it can change the contents), and if that is the case, it immediately sets the contents string to your difference in years.

You can see it works correctly: 1. Create a new document (or open an existing one). 2. Create a new Text Variable of type “Custom Text” and name it “experience”. Set its contents to some random text such as “oooh so clever”. 3. Insert this text variable somewhere in an appropriate place in the document text. For now, it’ll read “I have ooh so clever years of experience”. 4. Save and close the document. 5. The magic happens when opening this document again – please do so now!

If you followed all the steps above correctly, the text will now magically read “I have 43 years of experience”. And it will automatically update each new year!

Oh that is a nice catch! I’ve only used the most basic form of parameters, nothing really fancy, and this is really something to keep in mind. Kasyan’s summary is extremely helpful, describing this problem (oversight? bug?).

Well done on going all the way pursuing a solution!

I am not aware of any changes in the Undo functionality, but then again, maybe you found a bug.

There “should” not be a limit to the number of actions, but — well, maybe there is some kind of limit after all. Can you test if Undo works as expected with a smaller script? Or with less than your 100 actions?

The prettifying software of this forum automatically changed straight single and double quotes to “correct” curly opening and closing. And JavaScript cannot handle that! There is a minimal hint to this if you copied the code into Adobe’s own ExtendScript Toolkit Editor, or another code editor that does syntax-coloring: you can see text strings get a different color when you use the ‘correct’ type of quotes.

Trying again below; if it doesn’t work, delete the quotes one by one and replace them with *correct* correct straight ones.

app.findTextPreferences = null;
app.findTextPreferences.appliedParagraphStyle = "H2";
var myResults = app.activeDocument.findText();
for (i=0; i<myResults.length; i++)
	myResults[i].parentStory.paragraphs.nextItem(myResults[i].paragraphs[0]).appliedParagraphStyle = "No Indent Body"; 

Quite surprising: the official code SpecialCharacters.FOOTNOTE_SYMBOL does not insert anything at all! “Undo” also says “Undo Insert Text” as if something was inserted. But there is nothing there.

Other codes such as SpecialCharacters.AUTO_PAGE_NUMBER and SpecialCharacters.TRADEMARK_SYMBOL *do* work as expected.

That is specific enough to not exist anywhere. No sweat, though. Fortunately it is small enough and quick to write.

Select any of your threaded frames, and run this script. Be warned that it exactly does what it says on the tin: it blandly and blindly converts the text inside each frame to a single hyperlink by pasting “https://” in front of it and then connects that one link to its parent text frame. I have no idea what happens if there already is a link connected to the frame, or if you (accidentally or otherwise) have more text than a single link inside a text frame. Feel free to experiment, though :)

tc = app.selection[0].parentStory.textContainers;
for (f=0; f<tc.length; f++)
{
    src = app.activeDocument.hyperlinkPageItemSources.add(tc[f]);
    dest = app.activeDocument.hyperlinkURLDestinations.add('https://'+tc[f].contents.replace(/+$/, ''));
    app.activeDocument.hyperlinks.add(src, dest);
}

Already under discussion on https://forums.adobe.com/thread/2552042

(Please avoid cross-site duplicate discussions as it only leads to fragmented information.)