How to debug your charts with Chrome
The Chrome developer tools in undocked mode
When you first open the developer tools in Chrome (you can press CTRL+SHIFT+J to open the tools) they usually look like this - ie in undocked mode. You may prefer this as it gives you more space initially or you may find that showing them in docked mode is more convenient. The button for switching modes is highlighted.
The Chrome developer tools in docked mode
This is an old video from Google IO 2010 detailing the development tools. Remember that other browsers as well as Chrome have developer tools - so refer to their documentation for more details.
Debug functions in RGraph
Two functions that you may find very useful when you're debugging your charts are the $a() and the $p() functions. The $a() function is just a shorter alias for the standard alert() function whilst the $p() function is similar but goes further in that it attempts to "pretty print" the structure of whatever you pass it and also gives you type information. If you need to find out what a variable consists of then this is probably the function you want. However with larger objects it can cause the resulting dialog to extend offscreen.