Create Crosshair Guide

{
 // Access current composition
 var comp = app.project.activeItem;

 if (comp && (comp instanceof CompItem)) {
   app.beginUndoGroup("Create Guide Layer");

   // Create a new shape layer
   var shapeLayer = comp.layers.addShape();
   shapeLayer.name = "Center Guide";

   // Set layer as guide layer
   shapeLayer.guideLayer = true;

   // Vertical Line
   var verticalLineGroup = shapeLayer.property("ADBE Root Vectors Group").addProperty("ADBE Vector Group");
   verticalLineGroup.name = "Vertical Line";
   var verticalPath = verticalLineGroup.property("ADBE Vectors Group").addProperty("ADBE Vector Shape - Group");
   var verticalPathData = verticalPath.property("ADBE Vector Shape").value;
   verticalPathData.vertices = [[comp.width / 2, 0], [comp.width / 2, comp.height]];
   verticalPath.property("ADBE Vector Shape").setValue(verticalPathData);
   var verticalStroke = verticalLineGroup.property("ADBE Vectors Group").addProperty("ADBE Vector Graphic - Stroke");
   verticalStroke.property("ADBE Vector Stroke Color").setValue([1, 1, 1]);
   verticalStroke.property("ADBE Vector Stroke Width").setValue(2);

   // Horizontal Line
   var horizontalLineGroup = shapeLayer.property("ADBE Root Vectors Group").addProperty("ADBE Vector Group");
   horizontalLineGroup.name = "Horizontal Line";
   var horizontalPath = horizontalLineGroup.property("ADBE Vectors Group").addProperty("ADBE Vector Shape - Group");
   var horizontalPathData = horizontalPath.property("ADBE Vector Shape").value;
   horizontalPathData.vertices = [[0, comp.height / 2], [comp.width, comp.height / 2]];
   horizontalPath.property("ADBE Vector Shape").setValue(horizontalPathData);
   var horizontalStroke = horizontalLineGroup.property("ADBE Vectors Group").addProperty("ADBE Vector Graphic - Stroke");
   horizontalStroke.property("ADBE Vector Stroke Color").setValue([1, 1, 1]);
   horizontalStroke.property("ADBE Vector Stroke Width").setValue(2);

   // Slider Control for opacity
   var sliderControl = shapeLayer.property("ADBE Effect Parade").addProperty("ADBE Slider Control");
   sliderControl.name = "Opacity Control";
   sliderControl.property("Slider").setValue(100);
   var opacityProperty = shapeLayer.property("ADBE Transform Group").property("ADBE Opacity");
   opacityProperty.expression = 'effect("Opacity Control")("Slider")';

   // Set anchor point to center of layer
   var x_center = comp.width / 2;
   var y_center = comp.height / 2;
   shapeLayer.property("ADBE Transform Group").property("ADBE Anchor Point").setValue([x_center, y_center]);

   // Set layer position to center of composition
   shapeLayer.property("ADBE Transform Group").property("ADBE Position").setValue([x_center, y_center]);

   app.endUndoGroup();
 } else {
   alert("No active composition.");
 }
}

‍