There is a list of extensions here. Some are included already. They are
action
$$\require{action}\mathtip{\text{hover over this}}{e^x}$$
amsMath/amsSymbols (already included)
\begin{align}
&\text{align} \\
&\text{equations!}
\end{align}
amsCD
$$\begin{CD}
A @> x >> B\\
@V y V V @V V u V\\
C @>> v > D
\end{CD}$$
autobold
bolds math automatically $\require{autobold} x + y$
BBox (doesn't need a \require
?)
$$\bbox[red]{x+y}$$
begingroup
see The scope of \newcommand
is the entire page
cancel
$$\require{cancel} \cancel{x + y}$$
color
MathJax has a \color
built-in. See the MathJax docs or this thread for more information on what the color package does.
enclose
$$\require{enclose} \enclose{circle}{~~~x+y+z~~~}$$
extpfeil
$$\require{extpfeil} \Newextarrow{\xrightharpoonup}{5,10}{0x21C0} X \xrightharpoonup{f} Y$$
html
This one's blocked.
mhchem
$$\require{mhchem} \ce{C6H5-CHO}
\ce{$A$ ->[\ce{+H2O}] $B$}
\ce{SO4^2- + Ba^2+ -> BaSO4 v}$$
noErrors (already included?)
Not sure what this does
noUndefined (already included)
$$\badcommand$$
unicode (doesn't need a \require
)
$$\unicode[.55,0.05]{x22D6}$$
autoload-all
loads everything
Right click on the math and select "Show Math As->TeX Commands" to see what commands were used.