Microsoft has a very good page on Javascript programming in CRM – http://msdn.microsoft.com/en-us/library/hh771584.aspx
I was reading this today and I noticed it had a Javascript Programming Best Practices section. Javascript is very useful but I often feel the code produced in Javascript is not alway the best quality because there is no type checking and the process of writing the code and uploading is a bit of a hassle.
I have selected a couple of the best Practices but to read the full list go to the article
Microsoft have also created best practices for different versions, links to below to the different pages
CRM 2011 – Javascript best practices
CRM 2013 – Javascript best practices
CRM 2015 – Javascript best practices
There are a lot of best practices and it’s a really good article, but below are my top 4 best practices from the article. I would definitely recommend you read the different articles.
Use a Cross-browser JavaScript Library for HTML Web Resource User Interfaces
A cross-browser JavaScript library, such as jQuery, provides many advantages when developing HTML web resources that must support multiple browsers. JavaScript libraries like jQuery provide a unified development experience for all browsers supported by Microsoft Dynamics CRM. These capabilities are most appropriate when you are using HTML web resources to provide user interfaces. JavaScript libraries like jQuery provide consistent ways to interact with the Document Object Model (DOM).
Use Feature Detection When Writing Functions for Multiple Browsers
Even when you use a cross-browser library like jQuery, you need to be very aware of differences between browsers. You can generally detect which browser is being used by querying thenavigator.useragent property. This is called browser detection. Browser detection is not a good strategy for most cases because it can’t take into account what features newer versions of a browser have. Also, some browsers provide the capability to modify the navigation.useragent property so that they appear to be a different browser.
Feature detection is the recommended approach. By detecting what features are available, you can create code paths for the browsers you support without knowing exactly which browser is being used. For more information about feature detection, see How to Detect Features Instead of Browsers.
Define Unique Names for Your JavaScript Functions
When you are the only developer for an HTML page you can easily manage the names of the JavaScript functions you use. In Microsoft Dynamics CRM, other solutions may add JavaScript functions to the page where your function is used.
If two JavaScript functions on a page have the same name, the first function defined is overwritten by the second. For this reason, make sure that you define unique names for your JavaScript functions. For more information, see Creating Script Libraries.
Use Asynchronous Data Access Methods
When you access data by using the Microsoft Dynamics CRM web services that use the REST or SOAP endpoint for web resources, always use an XMLHttpRequest that is configured to execute asynchronously. The reason is that the browser operates on a single thread. If that thread is being used to execute a long-running process synchronously the browser will stop responding.
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