Javascript for Find and Replace the text in the .ai file

You can try this one:

//@target illustrator
function test (){
  var SEARCH_TEXT = "2021"; // TODO: Add other code to escape regular expressions for search text which has special characters other than digits/numbers.
  var REPLACE_TEXT = "2022";
  var SEARCH_RX = new RegExp(SEARCH_TEXT, "g");

  var folderWithFiles = Folder.selectDialog("Choose a folder with files");
  if (!folderWithFiles) { return; }
  var allFiles = folderWithFiles.getFiles();
  var thisFile, foundAiFiles = [];
  for (var i = 0; i < allFiles.length; i++) {
    thisFile = allFiles[i];
    if (thisFile.name.substr(-3) == ".ai") {
      foundAiFiles.push(thisFile);
    }
  }
  var fileReplacementLog = [], textReplacementLog = [];
  var thisDoc, thisText, currentFileWasReplaced;
  for (var i = 0; i < foundAiFiles.length; i++) {
    currentFileWasReplaced = false;
    thisFile = foundAiFiles[i];
    thisDoc = app.open(thisFile);
    textReplacementLog  = [];
    for (var j = 0; j < thisDoc.textFrames.length; j++) {
			thisText = thisDoc.textFrames[j];
      if (SEARCH_RX.test(thisText.contents)) {
        thisText.contents = thisText.contents.replace(SEARCH_RX, REPLACE_TEXT);
        textReplacementLog.push(thisText.uuid);
        currentFileWasReplaced = true;
      }
    }
    if (currentFileWasReplaced) {
      fileReplacementLog.push(decodeURI(thisFile.name) + " : " + textReplacementLog.join(", "));
      thisDoc.save(); // If this doesn't work to save, do a saveAs to a specified location.
      thisDoc.close(); // Should be already saved, but if not, use SaveOptions.SAVECHANGES
    } else {
			thisDoc.close(SaveOptions.DONOTSAVECHANGES);
		}
  }
  if (confirm("Done with " + foundAiFiles.length + " files. Write the process summary?")) {
		var summaryLocation = Folder("~/Desktop/TextReplacement");
		if (!summaryLocation.exists) {
			summaryLocation.create();
		}
    var summaryFile = File(decodeURI(summaryLocation) + "/summary-" + new Date().getTime() + ".txt");
    summaryFile.open("w");
    summaryFile.write(fileReplacementLog.join("\n"));
    summaryFile.close();
    summaryFile.execute();
  }
}
test();