Creates a New Mask within a pre-processing script

psNewMask.jsx

function psNewMask(showHide,appliedLayer){
    //"HdAl" - Hides; "RvlA" - Reveal All; "RvlS" - Reveal Selection
    
    try{
        app.activeDocument.activeLayer = doc.artLayers.getByName(appliedLayer); //variable must be string
    }
    catch(e){
    }   
    
    cTID = function(s) { return app.charIDToTypeID(s); }; 
    sTID = function(s) { return app.stringIDToTypeID(s); };
    
    var descMask = new ActionDescriptor();
        descMask.putClass(cTID("Nw  "), cTID("Chnl"));
            var refMask = new ActionReference();
            refMask.putEnumerated(cTID("Chnl"), cTID("Chnl"), cTID("Msk "));
        descMask.putReference(cTID("At  "), refMask);
        descMask.putEnumerated(cTID("Usng"), cTID("UsrM"), cTID(showHide));
    executeAction(cTID("Mk  "), descMask, DialogModes.NO);
}