Want to run batch process on TIFFs only

Here is a new version of the script that I previously posted to batch save .TIF files with LZW compression. This version will additionally process .tif files found in all sub-folders under the top-level input folder.

#target photoshop

// USE AT YOUR OWN RISK! TESTED ON MAC PHOTOSHOP CC 2019 ONLY

// Batch save TIF files from top-level and sub-level folders with LZW compression

// community.adobe.com/t5/Photoshop/Want-to-run-batch-process-on-TIFFs-only/m-p/10659870#M268352
// Want to run batch process on TIFFs only

// Special thanks to Paul MR for the recursive folder processing code!
// photoshopgurus.com/forum/threads/batch-and-subfolders.22134/
// batch and subfolders

alert('This script will resave all TIFF files with LZW compression. All sub-folders under the selected input folder will be processed.');

var imageFolder = Folder.selectDialog('Select the top-level folder with TIFF files to process');

var origDialogs = app.displayDialogs;
app.displayDialogs = DialogModes.NO;

// Script Execution Timer - Function    
var timeDiff = {
    setStartTime: function() {
        d = new Date();
        time = d.getTime();
    },
    getDiff: function() {
        d = new Date();
        t = d.getTime() - time;
        time = d.getTime();
        return t;
    }
};

// Script Execution Timer - Start    
timeDiff.setStartTime();

if (imageFolder != null) processFolder(imageFolder);

function processFolder(folder) {
    var fileList = folder.getFiles()
    for (var i = 0; i < fileList.length; i++) {
        var file = fileList[i];
        if (file instanceof File && file.name.match(/\.tif/i)) {
            open(file);

// Start Main Code Block
            var saveOpt = new TiffSaveOptions();
            saveOpt.imageCompression = TIFFEncoding.TIFFLZW;
            var aDoc = app.activeDocument;
            aDoc.saveAs(new File(aDoc.fullName), saveOpt);
            aDoc.close(SaveOptions.SAVECHANGES);
// End Main Code Block

        } else
        if (file instanceof Folder) {
            processFolder(file);
        }
    }
}

app.displayDialogs = origDialogs;

// Script Execution Timer - Finish    
alert('Batch LZW save completed! ' + '\r' + '(' + timeDiff.getDiff() / 1000 + ' seconds)');

// To Do: It would be nice to add a report on the number of files processed...