Scripting for layer activation/deactivation, colour change and export of PDF

Hello - new to scripting too so maybe we can both learn here. 

I'm no way the best scripter and there probably is a better method. But I managed to put something together that worked for my test files. 

I can get it to make a PDF but I cannot get the PDF dialog box to open work - never could

But you can export the PDF after it's finished doing the work.

So here was can blind open the documents in the book and toggle the layers as you said 

And there's a line here - so you put in tyour swatch colours (I can't use Yellow for some reason it's locked to the App so I made one called Yellow copy.

Replace these colours with your own names

replaceTableCellFill(doc, "Yellow copy", "Grey");

With no documents open - go to Window>Utilities>Scripts and run it - it will ask you to open the book file

then it should cycle the changes - I tested on a very basic document.

If it's not wroking the way you want could you please drop a few files for testing. Thanks.

TEST ON A DUPLICATE BOOK FILE (back up your book and all files first)

#target indesign

// ask for book file
var bookFile = File.openDialog("Select the Book file (.indb)", "*.indb");
if (!bookFile) {
    alert("No book selected.");
    exit();
}

// open the book
var book = app.open(File(bookFile));
var bookDocs = book.bookContents;

// Loop through book
for (var i = 0; i < bookDocs.length; i++) {
    var docPath = bookDocs[i].fullName;
    if (!File(docPath).exists) continue; // skip missing files

    // Open invisible
    var doc = app.open(File(docPath), false);

    // Toggle layers
    toggleLayers(doc, "Black", "CMYK");

    // Find/replace swatch in cells
    replaceTableCellFill(doc, "Yellow copy", "Grey");

    doc.save();
    doc.close();
}

// Save the book
book.save();

alert("All done!");

// --- FUNctions ---
function toggleLayers(doc, activateLayerName, deactivateLayerName) {
    var layers = doc.layers;
    for (var i = 0; i < layers.length; i++) {
        if (layers[i].name == activateLayerName) {
            layers[i].visible = true;
        }
        if (layers[i].name == deactivateLayerName) {
            layers[i].visible = false;
        }
    }
}

function replaceTableCellFill(doc, findSwatchName, changeSwatchName) {
    var findSwatch = doc.swatches.itemByName(findSwatchName);
    var changeSwatch = doc.swatches.itemByName(changeSwatchName);

    if (!findSwatch.isValid || !changeSwatch.isValid) {
        alert("Swatch '" + findSwatchName + "' or '" + changeSwatchName + "' not found.");
        return;
    }

    var tables = doc.stories.everyItem().tables.everyItem().getElements();
    for (var i = 0; i < tables.length; i++) {
        var cells = tables[i].cells;
        for (var j = 0; j < cells.length; j++) {
            if (cells[j].fillColor == findSwatch) {
                cells[j].fillColor = changeSwatch;
            }
        }
    }
}