This is a repost of
https://news.ycombinator.com/item?id=5937047 but a ton of work has gone into this library since then including support for Google Charts, D3 Treemaps, localization, cross-browser compatibility, error handling, mobile compatibility etc.
As a result, I release version 1.0 today :)
https://github.com/nicolaskruchten/pivottable/tree/v1.0.0