Suitelet script to add page init message

/**
 * @NApiVersion 2.1
 * @NScriptType Suitelet
 */
define(['N/record', 'N/ui/serverWidget','N/ui/message'],
    /**
 * @param{record} record
 * @param{serverWidget} serverWidget
     * @param{message} message
 */
    (record, serverWidget, message) => {
        /**
         * Defines the Suitelet script trigger point.
         * @param {Object} scriptContext
         * @param {ServerRequest} scriptContext.request - Incoming request
         * @param {ServerResponse} scriptContext.response - Suitelet response
         * @since 2015.2
         */
        const onRequest = (scriptContext) =>
        {
            try
            {
                if (scriptContext.request.method === 'GET')
                {
                    let poNumber = scriptContext.request.parameters.poID;
                    if(poNumber)
                    {
                        let form = serverWidget.createForm({title: poNumber + " " + " has been updated successfully"});
                        let messageObj = message.create({
                            type: message.Type.CONFIRMATION,
                            message: "SUCCESSFUL",
                            duration: 60000,
                        });
                        form.addPageInitMessage({message: messageObj});
                        scriptContext.response.writePage(form);
                    }
                    else
                    {
                        let form = serverWidget.createForm({title: " Sorry! The purchase order is not updated. Please try again later..."});
                        let messageObj = message.create({
                            type: message.Type.ERROR,
                            message: "FAILURE",
                            duration: 60000,
                        });
                        form.addPageInitMessage({message: messageObj});
                        scriptContext.response.writePage(form);

                    }
                }
            }
            catch (e)
            {
                log.debug("Error @Suitelet form 2",e);
            }
        }

        return {onRequest}

    });