Concerning this answer: How do I make \mapsto and \longmapsto point from right to left?

  • 2
    $\begingroup$ The suggestions given in Left version of \mapsto at TeX.SE don't work in mathjax :-( $\endgroup$ Oct 24, 2012 at 17:03
  • $\begingroup$ Here's a solution which works for me: \DeclareRobustCommand{\longleftmapsto}{\text{\reflectbox{\$\longmapsto\$}}} $\endgroup$ Dec 4, 2020 at 8:12

2 Answers 2


$\newcommand{\testleft}{\leftarrow\!\shortmid}\newcommand{\testleftlong}{\longleftarrow\!\shortmid}$ I was only able to come up with this:
which gives this: $\testleft$ and $\testleftlong$

The suggestions from Left version of \mapsto at TeX.SE don't work in mathjax: $\leftmapsto$, $\mapsfrom$.

  • $\begingroup$ For now, I'm going with this one. $\endgroup$ Oct 24, 2012 at 17:27
  • $\begingroup$ robjohn suggested this \longleftarrow{\raise{.4pt}{\hspace{-5pt}\shortmid}} in his comment. $\endgroup$ Oct 27, 2012 at 9:27

Unfortunately, \mapsfrom does not seem to be supported in MathJax, but that is what you are looking for, I believe. However, there is a \leftarrowtail: $\leftarrowtail$

There is a closed thread on the $\TeX$ board. The thread that this was closed as a duplicate of points to a useful tool: Detexify, which does not find the \mapsfrom symbol (for me at least).


I have found two alternatives; one that uses \unicode{x21a4} which gives $\unicode{x21a4}$, and another that uses \style{display:inline-block; transform:scale(-1,1);}{\mapsto} which gives $\style{display:inline-block; transform:scale(-1,1);}{\mapsto}$.

So adding
\newcommand{\mapsfrom}{\mathrel{\style{display:inline-block; transform:scale(-1,1);}{\mapsto}}}
should provide the missing \mapsfrom command.

  • $\begingroup$ Detexify gives me mapsfrom. $\endgroup$
    – Phira
    Oct 25, 2012 at 22:57
  • $\begingroup$ @Phira: After many tries, I did get \mapsfrom. However, \mapsfrom is not supported in MathJax. Something like $\longleftarrow{\raise{.4pt}{\hspace{-5pt}\shortmid}}$ could be used instead. $\endgroup$
    – robjohn Mod
    Oct 26, 2012 at 7:16

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