Regarding the index, if you are willing to visit the single-page version, a simple CTRL-F gives you the 70 references to "DOM", for instance. Your modern browser quickly shows how those references are spread in the document. That is pretty much an optimal index to me, with an unlimited number of entries, rendering the separate and physically constrained notion of index obsolete.

And why pages? In today's world of wildly diverse screen sizes and resolutions, please let the content flow. I remember being led to the wrong place of a book in my college years just because the edition I consulted happened to different from the author's, but I found that reasonable in the paper age. Semantically demarcated concepts such as chapters or sections have always been referred in this way, and rightly so. If you think about it, page numbers only helped you locate verbatim excerpts such as "to be, or not to be" in [2]. A completely valid and efficient artifact of the pre-digital era, which has now become dispensable, just as indexes have.

[1] http://dev.w3.org/html5/spec/headings-and-sections.html#outl...

[2] http://www.gutenberg.org/files/27761/27761-h/27761-h.htm

You would only need page numbers if there were any pages.