{Dynamics CRM Business Rules} Custom Xrm Script and Business Rules on the same Field in Dynamics CRM 2013

With the advent of Microsoft CRM 2013 in came business rules, a wonderful feature of the new CRM version. However with new implementations, there would be always some new confusions creeping up. Well in many training sessions on CRM 2013, i keep getting the question – “Will my onchange handlers and business rules work at the same time on the same field?”.
The best way to get the answer is to try out only. So let’s do a small test which i myself faced in one of my implementations. I was faced with a scenario where I had to to do whole lot of stuffs on change of field including clearing out certain other field values. All of them but clearing stuff was possible with business rules. So had to write a custom onchange event handler for the field. And yes both the business rules and my custom code triggered. Let’s see this with a simple example.
In the contact entity, for the email field I have a simple business rule which make the email field mandatory as soon as First Name field is entered/ changed by the user. Also for experimental purpose, I will register on on-change of First Name, to show a alert. Check for the screenshots below.


 
 
Now when I changed the First Name for a new Contact, first of all my custom jScript code fired. When I closed the alert by clicking OK, the Email field was set to Business Required by the Business Rule.


However remember the following MSDN Documentation – “When you set a field value by using a business rule, any OnChange event handlers for that
field will not run. This is to reduce the potential for a circular reference, which could lead to an infinite loop. ”
So when you are designing business rules and customer onchange handlers for your implementations, please do take all this into consideration.
Hope this helps!