To help you prepare for your upgrade to Microsoft Dynamics CRM 2013, we have created the Custom Code Validation Tool for Microsoft Dynamics CRM 2013. When using JavaScript code in Microsoft Dynamics CRM, it is possible that some code will stop working or cause an error when you upgrade.

The Microsoft Dynamics CRM Custom Code Validation Tool helps identify potential problems so that a developer can fix them. Please run this tool on your CRM instance to help identify potential issues with custom JavaScript in JavaScript libraries and HTML web resources. It will detect issues in the custom web resources that will no longer work after the upgrade is completed. The most common issues that this tool targets are:

•CRM v4 client SDK calls
•CRM 2007 end points
•Common DOM manipulations

Running this tool before upgrade will enable you to identify issues and fix them prior to your scheduled upgrade so that your upgrade process can run smoothly.

http://www.microsoft.com/en-us/download/details.aspx?id=30151