The "tocjs" transform type is an XHTML based output type that also generates a frameset and a JavaScript based table of contents with expandable and collapsible entries. The tocjs transform type was originally created by Shawn McKenzie as a plug-in to the toolkit, and later bundled with the default distribution.
The original tocjs output required an Ant build with several parameters in order to function properly; it also required a separate transform to XHTML in order to produce content. Beginning with DITA-OT release 1.5.4, the tocjs transform type was updated to always produce XHTML output and to use a default frameset when one is not already specified.
In release 1.5.4 the tocjs transform was also added to the build_demo.xml script as an option for the output type.