When you say 'form has been saved' do you mean for the first time? If so you can query the form type:- Xrm.Page.ui.getFormType;(Is it in Create or Update for example). If the form is already in Update mode then you can check if the form is dirty as you say. If you want to know which mandatory fields have not been completed you can also potentially loop over the attributes on the form and query whether they are Business Required or not:- Xrm.Page.data.entity.attributes.get('myAttribute').getRequiredLevel;and add this to a warning message to the user.
If the form is already in Update mode then you can check if the form is dirty - That way you know if any fields have been changed. Then you can look for all fields which are mandatory using the code above and check those fields have a value. If they don't you could add the field name to a warning message telling the user than this would need to be completed? As the other user commented though it is essentially reinventing the OOTB functionality, but it can be done if like you say the standard event has been prevented.–Apr 3 '12 at 14:15.
Crm Field Type
Making a Field Mandatory Based on Forms via JavaScript in Dynamics 365. CRM 2015 click dimensions MS CRM 2016 Marketing Field Service. CRM 2011: Set Currency in JavaScript. Archive CRM Development. Is not an option for me as this is happening during the creation of an entity and there is no guarantee that all the required fields are filled in at the time of the currency being set. (you may find code written for CRM 4.0 and you may need to convert the code as per CRM.