Get selected position in pixel on Illustrator

Illustrator_points_getter.js

var file = new File("~/Desktop/points.tsv"); // 出力先を指定
file.open("w");

var offsetX = 0;
var offsetY = -4271;
var doc = app.activeDocument;
var selection = doc.selection;

for (var i = selection.length - 1; i >= 0; i--) {
    var item = selection[i];
    var position = doc.convertCoordinate(item.position, app.coordinateSystem, CoordinateSystem.ARTBOARDCOORDINATESYSTEM);
    var x = position[0] + item.width * 0.5;
    var y = position[1] - item.height * 0.5;
    x = x - offsetX;
    y = y - offsetY;

    file.write(x + "\t" + y + "\n");  // オブジェクト名と座標をTSV形式で書き出し
}

file.close();
alert("TSV file with object names has been saved to your desktop.");