No you can combine both, which is the preferred way. As an example (although it does not use CWEB, but its own code) LaTeX's .docstrip/doc/dtx system does that. It generates the code, a driver and documentation both for code and user. It also produces an index automatically. You can use it to write your Javascript code if you want. As Wirth or maybe it was Hoare used to say code is literature as it is meant to be read by humans not only computers.
Fair. Though I think it is a safe to say that the intent is to document the software moreso than the use of it. Mainly going off of all of the programs on Knuth's homepage. TeX and METAFONT are both the same. The literate program is distinct from the user manuals.
