Hello,
you may start here: https://jazz.net/wiki/bin/view/Main/ReportsMain
Keeping in mind that the jazz Dev Wiki is provided as-is (no official support, may contain outdated information)

Thanks.
Eric.

Hi,

As for as I know is there no support by the built-in Eclipse debugger. Anyway did I find a kind of work-around to debug the Java Script in more ancient way.
There exists a rather interesting description on how to debug Java Script in BIRT reports using a popup window. More information about this can be found here http://www.lebirtexpert.com/wordpress/2010/03/03/using-a-popup-debug-window/.
Please notice that this can only be used in the report designer and not on the server. Therefore you're limited to the 1000 rows which are returned by the server, but in general it should be quite helpful to get some basic information about the variables and rows returned.

Btw, if you'd like to use it for charts as well it's necessary to define a function and a reference to it which needs to be available in a persistent global variable.

Regards
Matthias

I usually use some dynamic text items that display the values of the javascript variables. You can control the visibility of those items using a global javascript debug variable that you set to either true or false. But watch out as the hidden dynamic text could impact the performance of your report, especially if it gets bound to a data set.