Hi,
In crm 2011 we have best feature called web resources. What ever Jscript you creating in CRM 2011 you want to bring it has web resources. First create on web resource, select the type has Jscript in that you can add n number of Jscript functions whether
you can upload the file or write code in text editor. In entity you can add that web resource library and you can call whatever function related to that entity. You can add the same web resource library to all the entities.
For better understanding about web resources the following link will be helpful to you
http://blog.summitgroupsoftware.com/2010/11/web-resources-in-microsoft-dynamics-crm-2011/
Thanks & Regards, MS CRM Consultant, V.Surya. My Blog: http://inventcrm.wordpress.com/