I was working within CRM recently, attempting to configure some form level logic in order to display/hide fields, based on certain conditions on the form itself. I went into it rather gung-ho and immediately started writing the following JScript function:

function hideFormFields() 


    var myField = Xrm.Page.getAttribute("jg_myfield").getValue();

    if (myField = "Value1") {



    else if (myField = "Value2") {



I then suddenly thought “Hang on – can’t this be done via a Business Rule instead?”. For CRM Administrators who do not have any previous development skills, Business Rules were a godsend when Dynamics CRM 2013 was first released, having been continually improved since. They essentially enable you to implement conditional logic and actions on your entity forms, without the need of writing a single line of code. Business Rules are, in fact, a form of JScript, utilising many of the capabilities available as part of the XRM framework. As an excellent case in point, we can very easily replicate the above code into a Business Rule, like so:


There is an important lesson here, that anyone who works extensively within CRM needs to always remember; if it can be done out of the box within CRM, then why would you go to the trouble and effort to write a JScript function? Here are some reasons why CRM Developers should always think twice before typing away on that new form-level JScript function:

Business Rules actually do a lot more than you’d expect

This is something I am guilty of forgetting, and I’m having to train myself to consider this more carefully in future. In the above example, I made the immediate assumption that showing/hiding form fields on a conditional basis was not possible via a Business Rule – how very wrong I was! This seems to underline a general theme with how CRM customisers/developers approach Business Rules, assuming a glass half-empty approach. As of 2016 Update 1, as well as being able to modify a fields visibility, Business Rules can also support the following scenarios:

  • Show Error Message
  • Set Field Value – Fields can be set to match the value of another field, a specific value (including lookups), the result of a formula (Date/Number fields only) or be cleared of data.
  • Set Business Requirement.
  • Set Default Value – Fields can be set to match the value of another fields, a specific value (including lookups) or as the result of a formula (Date/Number fields only).
  • Lock or unlock field

What emerges, when combined with the conditional logic builder, is a means of utilising some of the most frequently used methods available to you via the SDK. And we can also hope and anticipate that as part of future releases of CRM, this list will be expanded on further.

Business Rules are supported, whereas your JScript may not be

To summarise another way, although you can do lots of things via Jscript within CRM, that doesn’t mean that you should. One thing I have observed with those who work with CRM, but have had more of a developer background, is that there is tendency to utilise methods/code which is not officially supported by Microsoft within CRM. Looking around the CRM community, and you often see that an unsupported solution is provided to a specific requirement, but often with no warning label attached to stress what it is doing. A good example of something which is unsupported is manipulating the Document Model Object (DOM) of the current page. Just because it works now doesn’t mean it will in the future, potentially causing major problems for your CRM deployment. If you are ever in doubt, be sure to review the supported extensions article on MSDN for CRM, and always think twice before you start using that nice bit of code you find on a Google search.

Your JScript may cause problems for end users

So your JScript is supported – great! But that doesn’t necessarily mean it’s going to work well from an end users perspective. If your JScript code, for example, does not provide a sufficient level of error handling, your end users could end up receiving error messages frequently. Or perhaps consider a scenario where your code is handling your errors well and outputting them correctly for potential debugging; this can lead to more lines of code that are unnecessary, and cause an impact when running the application on certain machines/browsers. With Business Rules, you don’t have to worry about addressing that careful balancing act between form loading times versus JScript library sizes. And, you can be assured that the CRM application as a whole will be able to handle your custom logic without affecting the performance of your deployment.

Jscript should have a time, place and bespoke requirement

What I mean by this is that JScript should only really begin to factor in when you are dealing with very specific, business requirements that the application “as-is” has no means of satisfying. An example of this is if you need to provide specific data validation to a field (such as a telephone number or bank sort code number). The only way this is ever going to be possible is via some kind of Regular Expression (RegEx) validation, which can only be performed via JScript. As one the key takeaways from this blog post, I would stress that you should always first attempt to build a Business Rule that is designed to meet the requirement that you are looking for, utilising other out of the box elements where appropriate (fields, workflows etc.). When it starts to become pretty obvious that a Business Rule is not going to cut it, then you can “give yourself permission” to start writing a JScript function 🙂

A “No Code First” approach should always prevail

I was recently introduced to this simple concept, but it is one that got me thinking and re-evaluating many of my previous solutions that I have built within CRM and elsewhere. When attempting to provide a potential solution to a requirement within CRM, you should try and put forward two solutions (where possible): a solution that can be achieved using out of the box functionality and one that requires bespoke coding to resolve. It may be that the first solution requires considerable time to build within CRM, but doing it this way could mean your solution is a lot more readable and understandable for those going into the system in future. By comparison, your 3-6 lines of code could prove to be virtually indecipherable.

So, in conclusion, can you guess what your new “Rule” should be moving forward?

Going back to my earlier example of your CRM Developer, AKA Former Application Developer, person, you can anticipate that they will have a very good knowledge of what CRM is capable from an SDK point of view. What may be lacking is a good understanding and knowledge of application as a whole, and specific features (such as SLA’s, Business Process Flows etc.). I would invite these people, and in fact anyone who works extensively with CRM, to focus their learning efforts towards the functional side of the application, so that they can ensure they have a good grasp of what CRM is capable of doing with, potentially, just a few mouse clicks. And, finally, to always think twice and consider alternative solutions before deciding on the best option – for everyone involved.

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