Things that KaTeX does not (yet) support
The list of supported/not supported functions is available at the documentation.
This is a list of functions, features, and extensions that KaTeX does not currently support. It is not comprehensive. Sources include KaTeX’s GitHub Issues pages and the list at http://utensil-site.github.io/available-in-katex/.
\oiint \oiiint
\brace \brack
\genfrac \above
\cline, \multicolumn, \hfill, \vline (#269)
⋗ ⋖ ¡
equation
picture
split
CD
Blackboard bold for small letters and digits (#473)
\cal
\oldstyle
\pmb
\textsc, i.e., small caps (#471)
Upright lower-case Greek (#564)
astrosymbols (#373)
\atopwithdelims, \overwithdelims
\bigominus, \bigoslash, \bigsqcap (#1222)
\buildrel
\cancelto
\dddot
\euro
\iddots (#1223)
\includegraphics (#898)
\leftroot, \uproot
\operatorname* (#1242)
\overbracket, \underbracket
\projlim, \varprojlim, \injlim, \varinjlim, \varliminf, \varlimsup
\sideset
\substack
\wideparen (#560)
\phase
\angl
\>
\hskip
\moveleft, \moveright
\mspace
\negthickspace, \negthinspace
\raisedistance
\rotatebox (#681)
\scalebox
\setlength (#687)
\shoveleft, \shoveright
\skew
\strut
\vcenter
\ce (#50)
\class, \cssId (#90)
Extension architecture (#762)
Right-to-left (#343)
\newcommand (#250) (KaTeX macros can be defined via \gdef or in the rendering options)
\DeclareMathOperator
\definecolor (#750)
\newenvironment (#37)
\renewenvironment
\require
Automatic left/right delimiters, as in nath package (#806)
Equation numbering (#350) (KaTeX supports \tag)
Canvas output
SVG output (#375)
Intermediate representation (HAST?)
\if, \fi, \ifx, \else, \ifmmode
| \array | KaTeX supports \begin{array} |
| \cases | KaTeX supports \begin{cases} |
| \class, \cssId | |
| \enclose | |
| \mathtip | |
| \Newextarrow | |
| \Rule | KaTeX supports \rule |
| \Space | KaTeX supports \space |
| \texttip | |
| \Tiny | KaTeX supports \tiny |
| \unicode |
