Duplicate an object into a marching crowd

Marching.js

var layer = selection[0];
var layerWidth = [[layer frame] width];
var layerHeight = [[layer frame] height];
var frame = [layer frame];
var parent = [layer parentGroup];

var widthOffset = layerWidth / 100 * 50;
var heightOffset = layerHeight / 100 * 60;

for (var row=0; row<5; row++) {
  for (var col=0; col<3; col++) {
    var clone = [layer duplicate];

    var frame2 = [clone frame];
    if (row % 2 == 1) {
      [frame2 setX: col * (layerWidth) + widthOffset];
    } else {
      [frame2 setX: col * (layerWidth) + widthOffset - widthOffset];
    }
    [frame2 setY: -row * (layerHeight - heightOffset)];
  }

  if (row % 2 == 0) {
    var clone = [layer duplicate];

    var frame2 = [clone frame];
    [frame2 setX: 3 * (layerWidth) + widthOffset - widthOffset];
    [frame2 setY: -row * (layerHeight - heightOffset)];
  }
  
}