Code to show alert in the suitelet page upon clicking the submit button

function alertMesage(scriptContext) {
            try {
                let html = '<script>alert("Wave have no itemfulfilment that satisfies the condition shipped and predispatch verification");location.replace("https://4976925-sb1.app.netsuite.com/app/site/hosting/scriptlet.nl?script=1565&deploy=1&compid=4976925_SB1&whence=");</script>';
                scriptContext.response.write(html);
            }
            catch (error) {
                log.error("error@ alertfunction", error);
            }
        }