PivotTable.js is a Javascript Pivot Table (aka Pivot Grid, Pivot Chart, Cross-Tab) implementation with drag'n'drop, written by Nicolas Kruchten.
PivotTable.js is a Javascript Pivot Table library with drag'n'drop functionality built on top of jQuery/jQueryUI and originally written in CoffeeScript by Nicolas Kruchten.
PivotTable.js' basic function is to turn a data set into a summary table and then optionally add a true 2-d drag'n'drop UI to allow a user to manipulate this summary table, turning it into a pivot table, very similar to the one found in older versions of Microsoft Excel with a bunch of extra developer-oriented features and some visualization effects.
Source & documentation: https://github.com/nicolaskruchten/pivottable
Examples: http://nicolas.kruchten.com/pivottable/examples/index.html