On Sat, 22 Oct 2016, B.A.Lee wrote:

> Sorry, I cannot help but ask for the functionalities that came with 
> Beamer. But these are the essential ones.

The ConTeXt stepping mechanism uses javascript and works only on Adobe 
Acrobat. For that reason, jI use some homegrown macros for stepping 
through my slides. These are not as feature rich as beamer macros, but get 
the work done.

I had not designed them for stepping through math, but they can be used 
for that purpose. For example, the following file:

\environment steps.tex
\setuppapersize[S5]

\starttext

\StartStepping 4
   \startformula
     \frac{ \ONLY 1 \phantom {-b  \ONLY 2 \phantom {{}\pm \sqrt{b^2 - 4ac}} }}
          { 2a }
   \stopformula

\StopStepping

\stoptext

gives the attached pdf file. If you want to use them to step through math, 
then it may be better to create a wrapper around \ONLY n \phantom to save 
some typing.

These were meant for private consumption, so they are not documented. But 
you can look at some examples of the resultant output at my website: 
http://www.ece.mcgill.ca/~amahaj1/talks.html

Aditya