Photoshop script that selects the next layer above or below even if it's not visible.

Select Next Layer (invisible or not).jsx

// Select Next Layer (+100).jsx
// Original Script: https://gist.github.com/joonaspaakko/048c9b58ccbb6e6f44c894bf4ce30b68
// This Script: https://gist.github.com/methodphoto/284a81728885873b4d5164aa977b7912
// This version of the original script will select the nth layer (in this case 100) below the current layer
// Using nextLayer('down'); you can switch directions using 'up' and 'down'
// Using 'Select next layer 100 times' you can choose how many layers it can skip

nextLayer('down');

// direction (↑): "up" or "above"
// direction (↓): "down" or "below"
function nextLayer(direction) {

  var doc = app.activeDocument;
  // Doc duplication is necessary because while the History panel can record visibility change, but for some reason it doesn't do that when the visibility command comes from a script... (AFAIK)
  var tempDoc = doc.duplicate();
  var layer1 = tempDoc.activeLayer;

  // Turn background layer into a normal layer
  var lastLayer = tempDoc.layers[tempDoc.layers.length - 1];
  function cTID(s) { return app.charIDToTypeID(s); }
  function sTID(s) { return app.stringIDToTypeID(s); }

  var layer1ID = activeLayerID();
  tempDoc.activeLayer = lastLayer;

  var bgLayerExists = lastLayer.isBackgroundLayer;
  if (bgLayerExists) { lastLayer.isBackgroundLayer = false; }

  try { selectLayerByID(layer1ID); } catch (e) {}

  // Select all layers
  var desc23 = new ActionDescriptor();
  var ref5 = new ActionReference();
  ref5.putEnumerated(cTID('Lyr '), cTID('Ordn'), cTID('Trgt'));
  desc23.putReference(cTID('null'), ref5);
  executeAction(sTID('selectAllLayers'), desc23, DialogModes.NO);

  // Make active layers visible
  var desc209 = new ActionDescriptor();
  var list93 = new ActionList();
  var ref129 = new ActionReference();
  ref129.putEnumerated(cTID('Lyr '), cTID('Ordn'), cTID('Trgt'));
  list93.putReference(ref129);
  desc209.putList(cTID('null'), list93);
  executeAction(cTID('Shw '), desc209, DialogModes.NO);

  // Reselect the starting layer
  if (bgLayerExists) { lastLayer.isBackgroundLayer = true; }
  selectLayerByID(layer1ID);

  // Select next layer 100 times
  var steps = 100;
  for (var i = 0; i < steps; i++) {
    try { snl(direction); } catch (e) { break; }
  }

  // Store the layer
  var nextLayer = activeLayerID();
  tempDoc.close(SaveOptions.DONOTSAVECHANGES);

  // Try to select the next layer using its ID
  try {
    selectLayerByID(nextLayer);
  }
  // If it fails, assume it did so because it was a background layer... and use another method for selecting that.
  catch (e) {
    var desc299 = new ActionDescriptor();
    var ref187 = new ActionReference();
    ref187.putName(cTID('Lyr '), "Background");
    desc299.putReference(cTID('null'), ref187);
    desc299.putBoolean(cTID('MkVs'), false);
    var list138 = new ActionList();
    list138.putInteger(1);
    desc299.putList(cTID('LyrI'), list138);
    executeAction(cTID('slct'), desc299, DialogModes.NO);
  }

  function snl(direction) {

    var select;
    if (direction == 'up' || direction == 'above') {
      select = cTID('Frwr');
    }
    else if (direction == 'down' || direction == 'below') {
      select = cTID('Bckw');
    }

    var desc67 = new ActionDescriptor();
    var ref41 = new ActionReference();
    ref41.putEnumerated(cTID('Lyr '), cTID('Ordn'), select);
    desc67.putReference(cTID('null'), ref41);
    desc67.putBoolean(cTID('MkVs'), false);
    var list17 = new ActionList();
    list17.putInteger(5);
    desc67.putList(cTID('LyrI'), list17);
    executeAction(cTID('slct'), desc67, DialogModes.NO);
  }

  function activeLayerID() {
    var ref = new ActionReference();
    ref.putProperty(charIDToTypeID("Prpr"), charIDToTypeID("LyrI"));
    ref.putEnumerated(charIDToTypeID("Lyr "), charIDToTypeID("Ordn"), charIDToTypeID("Trgt"));
    return executeActionGet(ref).getInteger(stringIDToTypeID("layerID"));
  }

  function selectLayerByID(id, add) {
    add = (add == undefined) ? false : add;
    var ref = new ActionReference();
    ref.putIdentifier(cTID('Lyr '), id);
    var desc = new ActionDescriptor();
    desc.putReference(cTID('null'), ref);
    if (add) {
      desc.putEnumerated(sTID('selectionModifier'), sTID('selectionModifierType'), sTID('addToSelection'));
    }
    desc.putBoolean(cTID('MkVs'), false);
    executeAction(cTID('slct'), desc, DialogModes.NO);
  }

}