How to use the D3.JS library for data visualization?
There are at least 3 contributed modules which may help to use the D3.js library (open source, released under the BSD license) in a Drupal 7 site:


Charts and Graphs:


  Charts and Graphs is an API for developers. It can be extended by third-party modules that want to add their own charting implementations. It does nothing by itself. It should only be installed if some other module requires it.

D3 (Alfa release only):


  creates visualizations as libraries (alpha version only) which allows one to add/remove visualizations, share them between modules, and integrate them with (for example: Views) through library .info files.


The Basic module configuration presentation provides a short intro about how to use the module in combination with Views.
Forena


Comment 7 in issue 2364427 contains an example of a custom module to use the Forena module for creating charts using the d3.js library.
Issue # 2383509 describes the approaches for using D3 with Forena.



If you decide to not use any of these modules, it may help to get started with D3.js integration in Drupal by just looking at the code of these modules. Either to roll your own D3.js cookies via a custom module, or at least to get an idea of the required effort.

The D3.JS Tutorial is a great place for documentation about how to use this library.