ERPNext - Button in list view

custom_script_po.js

frappe.listview_settings['Purchase Order'] = {
    button: {
        show: function(doc) {
            return true;
        },
        get_label: function() {
            return __('View');
        },
        get_description: function(doc) {
            return __('Print {0}', [doc.name])
        },
        action: function(doc) {
            //frappe.set_route("/app/print/Purchase Order/" + doc.name);
            
            var objWindowOpenResult = window.open(frappe.urllib.get_full_url("/printview?"
              + "doctype=" + encodeURIComponent("Purchase Order")
              + "&name=" + encodeURIComponent(doc.name)
              + "&trigger_print=0"
              + "&format=General"
              + "&no_letterhead=0"
              + "&_lang=tr"
            ));

            if(!objWindowOpenResult) {
              msgprint(__("Please set permission for pop-up windows in your browser!")); return;
            }
        }
    }
}