"buttons": ["copy", {
                    extend: "csv",
                    text: "CSV",
                    action: function(e, dt, button, config) {
                        pageTitle.innerHTML = "PURCHASE REGISTER REPORT";
                        $.fn.dataTable.ext.buttons.csvHtml5.action.call(this, e, dt, button, config);
                    }
                }, {
                    extend: "excel",
                    text: "Excel",
                    action: function(e, dt, button, config) {
                        // Your custom onClick function here

                        pageTitle.innerHTML = "PURCHASE REGISTER REPORT";
                        console.log("Excel button clicked!");
                        $.fn.dataTable.ext.buttons.excelHtml5.action.call(this, e, dt, button, config);
                    }
                }, {
                    extend: "pdf",
                    text: "PDF",
                    action: function(e, dt, button, config) {
                        pageTitle.innerHTML = "PURCHASE REGISTER REPORT";
                        console.log("PDF button clicked!");
                        $.fn.dataTable.ext.buttons.pdfHtml5.action.call(this, e, dt, button, config);
                    }
                },
                {
                    extend: "print",
                    text: "Print",
                    action: function(e, dt, button, config) {
                        pageTitle.innerHTML = "PURCHASE REGISTER REPORT";
                        console.log("Print button clicked!");
                        $.fn.dataTable.ext.buttons.print.action.call(this, e, dt, button, config);
                    }
                }, "colvis"
            ]