If you want to show warning message in sales order when selecting a particular checkbox, use the following code in UserEvent Script.
Must include the module N/ui/message and give newRec type is sales order.
let newRec=scriptContext.newRecord.
let cusField=newRec.getValue({fieldId:’fieldid’});
if(cusField) {
let myMsg = message.create({
title: “Title”,
message: ‘Message’,
type: message.Type.WARNING,
});
scriptContext.form.addPageInitMessage({message: myMsg});
}
In the ‘fieldid’, you give your fieldid and give required details in ‘Title’, and ‘Message’. The message types are CONFIRMATION, INFORMATION ,WARNING and ERROR.