Need help searching through sub-directories

I need to search through multiple subdirectories, which contain exactly 2 images in each. One original image and one possible updated image.

I then need to compare the 2 imagesnewLayer.blendMode = BlendMode.DIFFERENCE; and log whether there are differences or not.

I cannot figure out how to recurse through subdirectories properly.  My current script looks like this:

#target photoshop

function main() {

    var errorlog = File(Folder.desktop + "/Test_Log.txt");

    var d =new Date;

//    errorlog.open('w');// write

    errorlog.open('a');// append

    errorlog.writeln(d); // date

// This section shows how to set up user selected images

    var mySelectFile1 = File.openDialog("Selection prompt");

    if(mySelectFile1 != null) app.open(mySelectFile1);

    var mySelectFile2 = File.openDialog("Selection prompt");

    if(mySelectFile2 != null) app.open(mySelectFile2);

// Making the selected images variables

    var doc1 = app.open(mySelectFile1);

    var doc2 = app.open(mySelectFile2);

// Selecting entire doc2 image and copying

    doc2.selection.selectAll();

    doc2.selection.copy();

// Setting doc1 to active document

    app.activeDocument = doc1;

// Pasting doc2 into new layer in doc1

    var newLayer = doc1.paste();

// Selecting the difference BlendMode option in layers

    newLayer.blendMode = BlendMode.DIFFERENCE;

// Checking histogram to see if there is any difference between layers (doc1 as background and doc2 as new layer)

    found=0

    var histogram = doc1.histogram;

    for (var i = 1; i < histogram.length; ++i) {

        if (histogram[i] > 0)

            found=1

    }

// log output

    if (found) {

        errorlog.writeln(doc1.name + "," + doc2.name  + ",Differences_Found")

        }

    else {

        errorlog.writeln(doc1.name + "," + doc2.name  + ",Exact_Match")

        }

// close all open documents without saving

    while (documents.length > 0) {

        activeDocument.close(SaveOptions.DONOTSAVECHANGES);

}

    errorlog.close();

    errorlog.execute();

    return;

}

main ()

Thank you.