I am not clear, may be you are looking like this,
var TargetFolder= Folder.selectDialog("Select a target");
//alert(TargetFolder.fsName);
var targetFileName = TargetFolder.fsName.toString();
targetFileName = targetFileName.replace("/users/test/desktop/", "");
targetFileName = targetFileName.replace("copy here/", "");
alert(targetFileName);
Vandy